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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<title>Inform 6 Objects</title>
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<!--Weave of 'Inform 6 Objects' generated by Inweb-->
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<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../intern.html">Inter Modules</a></li><li><a href="index.html">final</a></li><li><a href="index.html#4">Chapter 4: Inform 6</a></li><li><b>Inform 6 Objects</b></li></ul></div>
<p class="purpose">To declare I6 objects, classes, attributes and properties.</p>
<ul class="toc"><li><a href="4-i6o.html#SP2">§2. A disclaimer</a></li><li><a href="4-i6o.html#SP3">§3. Property declarations</a></li><li><a href="4-i6o.html#SP5">§5. Kinds, instances and property values</a></li><li><a href="4-i6o.html#SP13">§13. A few resources</a></li></ul><hr class="tocbar">
<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>§1. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::create_generator</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::create_generator</span></span>:<br/>Generating Inform 6 - <a href="4-fi6.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">DECLARE_PROPERTY_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP4" class="function-link"><span class="function-syntax">I6TargetObjects::declare_property</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">DECLARE_KIND_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP5" class="function-link"><span class="function-syntax">I6TargetObjects::declare_kind</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">END_KIND_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP6" class="function-link"><span class="function-syntax">I6TargetObjects::end_kind</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">DECLARE_INSTANCE_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP7" class="function-link"><span class="function-syntax">I6TargetObjects::declare_instance</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">END_INSTANCE_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP8" class="function-link"><span class="function-syntax">I6TargetObjects::end_instance</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">ASSIGN_PROPERTY_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP11" class="function-link"><span class="function-syntax">I6TargetObjects::assign_property</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">ASSIGN_PROPERTIES_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP12" class="function-link"><span class="function-syntax">I6TargetObjects::assign_properties</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">PSEUDO_OBJECT_MTID</span><span class="plain-syntax">, </span><a href="4-i6o.html#SP10" class="function-link"><span class="function-syntax">I6TargetObjects::pseudo_object</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>§2. A disclaimer. </b>The two virtual machines compiled to by I6 both support "properties" and
"attributes" attached to "objects" of "classes". We will use all of those features, but
not in a way which exactly matches their similarly-named I7 features. So for
clarity we will call them VN-properties, VM-attributes, VM-objects and VM-classes
in this section of code. For example, this I6 code:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="identifier-syntax">Object</span><span class="plain-syntax"> </span><span class="identifier-syntax">mandrake_root</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">class</span><span class="plain-syntax"> </span><span class="identifier-syntax">Mandragora</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">with</span><span class="plain-syntax"> </span><span class="identifier-syntax">potency</span><span class="plain-syntax"> </span><span class="constant-syntax">10</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">has</span><span class="plain-syntax"> </span><span class="identifier-syntax">edible</span><span class="plain-syntax">;</span>
</pre>
<p class="commentary">creates a VM-object <span class="extract"><span class="extract-syntax">mandrake_root</span></span> of VM-class <span class="extract"><span class="extract-syntax">Mandragora</span></span>, which has the
VM-property <span class="extract"><span class="extract-syntax">potency</span></span> set to 10, and the VM-attribute <span class="extract"><span class="extract-syntax">edible</span></span> set.
</p>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>§3. Property declarations. </b>Here we must declare properties. Some will be stored in VM-properties, others
in VM-attributes. Owing to a quirk of the I6 language, VM-properties do not
need to be declared before use, though VM-attributes do. The decisions we take
are motivated by the following considerations:
</p>
<ul class="items"><li>(a) The supply of VM-attributes is limited, so we cannot simply store all
either-or properties in VM-attributes: there might be too many.
</li><li>(b) The supply of declared VM-properties is also limited (though not of
undeclared ones).
</li><li>(c) But VM-attributes, and declared VM-properties, can be accessed just a
little faster at runtime, and take just a little less storage.
</li></ul>
<p class="commentary">Because of (c) we don't want to do the simplest possible thing — i.e., to
make everything an undeclared VM-property and be done with it. Instead, we
do use our limited supplies of (a) and (b), prioritising properties which
come from kits because that will include all the most frequently-used ones.
</p>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>§4. </b>Like any generator, we also have to decide what to put into the first two
words in the metadata array for an I7 property. Since we are using a mixed
strategy for how to store properties, this metadata will have to identify
in each case what is being done. Word 0 will be either 1 or 2, meaning "store
in a VM-property" or "store in a VM-attribute", respectively. Word 1 will
then be the choice of VM-property or VM-attribute in question. For example,
hypothetical I7 properties "potency" and "edible" might have metadata arrays
like so:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> A_potency --> 1</span>
<span class="plain-syntax"> potency</span>
<span class="plain-syntax"> 0 (means "not either-or")</span>
<span class="plain-syntax"> ... (permissions)</span>
<span class="plain-syntax"> A_edible --> 2</span>
<span class="plain-syntax"> edible</span>
<span class="plain-syntax"> 1 (means "either-or")</span>
<span class="plain-syntax"> ... (permissions)</span>
</pre>
<p class="commentary">Note that at runtime VM-property and VM-attribute numbers may overlap — so
there is no way to tell from word 1 alone whether it is intended to be a
VM-property number or a VM-attribute number. Indeed, <span class="extract"><span class="extract-syntax">potency</span></span> might compile
to the same number as <span class="extract"><span class="extract-syntax">edible</span></span>. So word 0 is certainly necessary.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::declare_property</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::declare_property</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">all_forms</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inner_name</span><span class="plain-syntax"> = </span><a href="2-vo.html#SP3" class="function-link"><span class="function-syntax">VanillaObjects::inner_property_name</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">originated_in_a_kit</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_1" class="named-paragraph-link"><span class="named-paragraph">Find whether this property has been assimilated from a kit</span><span class="named-paragraph-number">4.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_2" class="named-paragraph-link"><span class="named-paragraph">Decide whether to store this in a VM-attribute</span><span class="named-paragraph-number">4.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax">) </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_3" class="named-paragraph-link"><span class="named-paragraph">Declare a VM-attribute to store this in</span><span class="named-paragraph-number">4.3</span></a></span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">originated_in_a_kit</span><span class="plain-syntax">) </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_4" class="named-paragraph-link"><span class="named-paragraph">Declare a VM-property to store this in</span><span class="named-paragraph-number">4.4</span></a></span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_5" class="named-paragraph-link"><span class="named-paragraph">Store this in an undeclared VM-property</span><span class="named-paragraph-number">4.5</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_6" class="named-paragraph-link"><span class="named-paragraph">Compile the two opening words of the property metadata</span><span class="named-paragraph-number">4.6</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4_1" class="paragraph-anchor"></a><b>§4.1. </b>For why there are multiple declarations of the same property in the Inter
tree, see <a href="2-vo.html" class="internal">Vanilla Objects</a>. If any one of them came from a kit, we consider
that definition to be the true one.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Find whether this property has been assimilated from a kit</span><span class="named-paragraph-number">4.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">p</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax">, </span><span class="identifier-syntax">all_forms</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">SymbolAnnotation::get_b</span><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">ASSIMILATED_IANN</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">originated_in_a_kit</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4">§4</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_2" class="paragraph-anchor"></a><b>§4.2. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Decide whether to store this in a VM-attribute</span><span class="named-paragraph-number">4.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP10" class="function-link"><span class="function-syntax">VanillaObjects::is_either_or_property</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NOT_APPLICABLE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_2_1" class="named-paragraph-link"><span class="named-paragraph">Any either/or property which can belong to a value instance is ineligible</span><span class="named-paragraph-number">4.2.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_2_2" class="named-paragraph-link"><span class="named-paragraph">An either/or property coming from a kit must be chosen</span><span class="named-paragraph-number">4.2.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP4_2_3" class="named-paragraph-link"><span class="named-paragraph">Otherwise give away attribute slots on a first-come-first-served basis</span><span class="named-paragraph-number">4.2.3</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> == </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">p</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax">, </span><span class="identifier-syntax">all_forms</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">InterSymbol::set_flag</span><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">ATTRIBUTE_MARK_ISYMF</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">p</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax">, </span><span class="identifier-syntax">all_forms</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">InterSymbol::clear_flag</span><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">ATTRIBUTE_MARK_ISYMF</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"No decision was taken"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4">§4</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_2_1" class="paragraph-anchor"></a><b>§4.2.1. </b>In the virtual machine, only VM-objects can have VM-attributes, and instances
of non-object kinds are not going to be implemented as VM-objects. So if a
property needs to be given to such a kind, we cannot store it in a VM-attribute.
For example:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="identifier-syntax">Colour</span><span class="plain-syntax"> </span><span class="identifier-syntax">is</span><span class="plain-syntax"> </span><span class="identifier-syntax">a</span><span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> </span><span class="identifier-syntax">of</span><span class="plain-syntax"> </span><span class="identifier-syntax">value</span><span class="plain-syntax">. </span><span class="identifier-syntax">The</span><span class="plain-syntax"> </span><span class="identifier-syntax">colours</span><span class="plain-syntax"> </span><span class="identifier-syntax">are</span><span class="plain-syntax"> </span><span class="identifier-syntax">red</span><span class="plain-syntax">, </span><span class="identifier-syntax">green</span><span class="plain-syntax"> </span><span class="identifier-syntax">and</span><span class="plain-syntax"> </span><span class="identifier-syntax">blue</span><span class="plain-syntax">. </span><span class="identifier-syntax">A</span><span class="plain-syntax"> </span><span class="identifier-syntax">colour</span>
<span class="identifier-syntax">can</span><span class="plain-syntax"> </span><span class="identifier-syntax">be</span><span class="plain-syntax"> </span><span class="identifier-syntax">garish</span><span class="plain-syntax"> </span><span class="identifier-syntax">or</span><span class="plain-syntax"> </span><span class="identifier-syntax">dowdy</span><span class="plain-syntax">.</span>
</pre>
<p class="commentary">Here "red", "green" and "blue" are not going to be represented by VM-objects
at runtime: they will be the numbers 1, 2, and 3. So the property "garish"
cannot be a VM-attribute. (Numbers can't, of course, have VM-properties
either, but see below for how we get around that.)
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Any either/or property which can belong to a value instance is ineligible</span><span class="named-paragraph-number">4.2.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">p</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax">, </span><span class="identifier-syntax">all_forms</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP9" class="function-link"><span class="function-syntax">VanillaObjects::is_property_of_values</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">p</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4_2">§4.2</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_2_2" class="paragraph-anchor"></a><b>§4.2.2. </b>We give priority to properties declared in kits, since those in WorldModelKit
and CommandParserKit are by far the most frequently used.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">An either/or property coming from a kit must be chosen</span><span class="named-paragraph-number">4.2.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">originated_in_a_kit</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4_2">§4.2</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_2_3" class="paragraph-anchor"></a><b>§4.2.3. </b>We have in theory 48 VM-attributes to use up, that being the number
available in versions 5 and higher of the Z-machine VM, but the standard
kits consume so many that only a few slots remain for the user's own
creations. Giving these away to the first-created properties is the
simplest way to allocate them, and in fact that works pretty well, because
the first such either/or properties tend to be created in extensions and
to be frequently used.
</p>
<pre class="definitions code-font"><span class="definition-keyword">define</span> <span class="constant-syntax">ATTRIBUTE_SLOTS_TO_GIVE_AWAY</span><span class="plain-syntax"> </span><span class="constant-syntax">11</span>
</pre>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Otherwise give away attribute slots on a first-come-first-served basis</span><span class="named-paragraph-number">4.2.3</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NOT_APPLICABLE</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">I6_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">attribute_slots_used</span><span class="plain-syntax">)++ < </span><span class="constant-syntax">ATTRIBUTE_SLOTS_TO_GIVE_AWAY</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4_2">§4.2</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_3" class="paragraph-anchor"></a><b>§4.3. </b>Okay, declaration time. The I6 <span class="extract"><span class="extract-syntax">Attribute</span></span> directive creates a VM-attribute.
We give it the property's "inner name": see <a href="2-vo.html" class="internal">Vanilla Objects</a> for why.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Declare a VM-attribute to store this in</span><span class="named-paragraph-number">4.3</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">attributes_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">), </span><span class="string-syntax">"Attribute %S;\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">inner_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4">§4</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_4" class="paragraph-anchor"></a><b>§4.4. </b>And the <span class="extract"><span class="extract-syntax">Property</span></span> directive declares a VM-property.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Declare a VM-property to store this in</span><span class="named-paragraph-number">4.4</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">properties_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">), </span><span class="string-syntax">"Property %S;\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">inner_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4">§4</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_5" class="paragraph-anchor"></a><b>§4.5. </b>It may seem that nothing needs to be done in order to declare an undeclared
VM-property: so why is there code here? In fact, old-time Inform 6 coders will
recognise this situation. Suppose we have a property called <span class="extract"><span class="extract-syntax">example</span></span>, and
we have some I6 code making reference to it:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">[ </span><span class="identifier-syntax">EnthuseOver</span><span class="plain-syntax"> </span><span class="identifier-syntax">p</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">p</span><span class="plain-syntax"> == </span><span class="identifier-syntax">example</span><span class="plain-syntax">) </span><span class="string-syntax">"Hey, the example property</span><span class="comment-syntax">How about that!";</span>
<span class="string-syntax"> "</span><span class="identifier-syntax">Shucks</span><span class="plain-syntax">, </span><span class="identifier-syntax">just</span><span class="plain-syntax"> </span><span class="identifier-syntax">another</span><span class="plain-syntax"> </span><span class="identifier-syntax">anonymous</span><span class="plain-syntax"> </span><span class="identifier-syntax">property</span><span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> </span><span class="identifier-syntax">the</span><span class="plain-syntax"> </span><span class="identifier-syntax">pile</span><span class="plain-syntax">.</span><span class="string-syntax">"</span>
<span class="string-syntax">];</span>
</pre>
<p class="commentary">But now suppose that the I6 user has this code available but has, in fact,
never actually given the <span class="extract"><span class="extract-syntax">example</span></span> property to any object. That means it is
never implicitly declared as a VM-property; and so it does not exist as an
identifier name, which leads to the <span class="extract"><span class="extract-syntax">EnthuseOver</span></span> function failing to compile.
We get around this with a trick called "stubbing the property": placing the
following precautionary code at the end of the program —
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">#</span><span class="identifier-syntax">ifndef</span><span class="plain-syntax"> </span><span class="identifier-syntax">example</span><span class="plain-syntax">; </span><span class="reserved-syntax">Constant</span><span class="plain-syntax"> </span><span class="identifier-syntax">example</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">; #</span><span class="identifier-syntax">endif</span><span class="plain-syntax">;</span>
</pre>
<p class="commentary">Now <span class="extract"><span class="extract-syntax">example</span></span> exists. It's not a valid VM-property, so it will never be seen
in the wild. <span class="extract"><span class="extract-syntax">EnthuseOver</span></span> will never really enthuse, but won't throw syntax
errors either.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Store this in an undeclared VM-property</span><span class="named-paragraph-number">4.5</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">property_stubs_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">), </span><span class="string-syntax">"#ifndef %S; Constant %S = 0; #endif;\n"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inner_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">inner_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4">§4</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4_6" class="paragraph-anchor"></a><b>§4.6. </b>Finally, the opening words of the metadata array. This is done in a rather
odd-looking way because of yet another oddity in the I6 compiler whereby not all
VM-property names can be used as array entries, whereas they can all be used
as values of defined <span class="extract"><span class="extract-syntax">Constant</span></span>s. (This in particular is true of the special
property <span class="extract"><span class="extract-syntax">name</span></span>.) So we define
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">Constant</span><span class="plain-syntax"> </span><span class="identifier-syntax">subterfuge_20</span><span class="plain-syntax"> = </span><span class="identifier-syntax">example</span><span class="plain-syntax">;</span>
<span class="reserved-syntax">Array</span><span class="plain-syntax"> </span><span class="identifier-syntax">P_edible</span><span class="plain-syntax"> --> </span><span class="constant-syntax">1</span><span class="plain-syntax"> </span><span class="identifier-syntax">subterfuge_20</span><span class="plain-syntax"> ...</span>
</pre>
<p class="commentary">rather than:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">Array</span><span class="plain-syntax"> </span><span class="identifier-syntax">P_edible</span><span class="plain-syntax"> --> </span><span class="constant-syntax">1</span><span class="plain-syntax"> </span><span class="identifier-syntax">example</span><span class="plain-syntax"> ...</span>
</pre>
<p class="commentary">The intent of these is the same, of course.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Compile the two opening words of the property metadata</span><span class="named-paragraph-number">4.6</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">I6_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">subterfuge_count</span><span class="plain-syntax">)++;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">constants_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">), </span><span class="string-syntax">"Constant subterfuge_%d = %S;\n"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">I6_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">subterfuge_count</span><span class="plain-syntax">), </span><span class="identifier-syntax">inner_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">, </span><span class="string-syntax">"%d"</span><span class="plain-syntax">, (</span><span class="identifier-syntax">store_in_VM_attribute</span><span class="plain-syntax">)?2:1);</span>
<span class="plain-syntax"> </span><a href="2-cg2.html#SP10" class="function-link"><span class="function-syntax">Generators::array_entry</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">val</span><span class="plain-syntax">, </span><span class="constant-syntax">WORD_ARRAY_FORMAT</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Str::clear</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">, </span><span class="string-syntax">"subterfuge_%d"</span><span class="plain-syntax">, </span><span class="identifier-syntax">I6_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">subterfuge_count</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><a href="2-cg2.html#SP10" class="function-link"><span class="function-syntax">Generators::array_entry</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">val</span><span class="plain-syntax">, </span><span class="constant-syntax">WORD_ARRAY_FORMAT</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">)</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP4">§4</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>§5. Kinds, instances and property values. </b>The following is called for all kinds which can have properties. We divide
them in two:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::declare_kind</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::declare_kind</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">, </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> *</span><span class="identifier-syntax">saved</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax"> == </span><span class="identifier-syntax">RunningPipelines::get_symbol</span><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">from_step</span><span class="plain-syntax">, </span><span class="identifier-syntax">object_kind_RPSYM</span><span class="plain-syntax">)) ||</span>
<span class="plain-syntax"> (</span><a href="2-vo.html#SP7" class="function-link"><span class="function-syntax">VanillaObjects::is_kind_of_object</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">)))</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP5_1" class="named-paragraph-link"><span class="named-paragraph">A kind of object, including the kind object itself</span><span class="named-paragraph-number">5.1</span></a></span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP8" class="function-link"><span class="function-syntax">VanillaObjects::value_kind_with_properties</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP5_2" class="named-paragraph-link"><span class="named-paragraph">A property-holding enumeration kind</span><span class="named-paragraph-number">5.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP5_1" class="paragraph-anchor"></a><b>§5.1. </b>Each object kind is compiled to a VM-class:
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">A kind of object, including the kind object itself</span><span class="named-paragraph-number">5.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> *</span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">classes_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">class_name</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbol::trans</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">super_class</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">super_name</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TypenameInstruction::super</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">super_name</span><span class="plain-syntax">) </span><span class="identifier-syntax">super_class</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbol::trans</span><span class="plain-syntax">(</span><span class="identifier-syntax">super_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"Class %S\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">class_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Str::len</span><span class="plain-syntax">(</span><span class="identifier-syntax">super_class</span><span class="plain-syntax">) > </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" class %S\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">super_class</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP5">§5</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP5_2" class="paragraph-anchor"></a><b>§5.2. </b>Each enumeration kind is compiled to a VM-object called its "value property holder",
or VPH. The instances of the kind are enumerated 1, 2, 3, ... at runtime; if
the kind is to have a property, then we store those property values in an array
indexed by instance, and put the address of that array in a VM-property attached
to the VPH VM-object.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">A property-holding enumeration kind</span><span class="named-paragraph-number">5.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">instance_name</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">instance_name</span><span class="plain-syntax">, </span><span class="string-syntax">"VPH_%d"</span><span class="plain-syntax">, </span><a href="2-vo.html#SP6" class="function-link"><span class="function-syntax">VanillaObjects::weak_id</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_object_header</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"Object"</span><span class="plain-syntax">, </span><span class="identifier-syntax">instance_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, -1, </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">instance_name</span><span class="plain-syntax">)</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP5">§5</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>§6. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::end_kind</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::end_kind</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">, </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax"> == </span><span class="identifier-syntax">RunningPipelines::get_symbol</span><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">from_step</span><span class="plain-syntax">, </span><span class="identifier-syntax">object_kind_RPSYM</span><span class="plain-syntax">)) ||</span>
<span class="plain-syntax"> (</span><a href="2-vo.html#SP7" class="function-link"><span class="function-syntax">VanillaObjects::is_kind_of_object</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">))) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">";\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP8" class="function-link"><span class="function-syntax">VanillaObjects::value_kind_with_properties</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_object_footer</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>§7. </b>Instances next:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::declare_instance</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::declare_instance</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inst_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">enumeration</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> *</span><span class="identifier-syntax">saved</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax"> == </span><span class="identifier-syntax">RunningPipelines::get_symbol</span><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">from_step</span><span class="plain-syntax">, </span><span class="identifier-syntax">object_kind_RPSYM</span><span class="plain-syntax">)) ||</span>
<span class="plain-syntax"> (</span><a href="2-vo.html#SP7" class="function-link"><span class="function-syntax">VanillaObjects::is_kind_of_object</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">)))</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP7_1" class="named-paragraph-link"><span class="named-paragraph">An object instance</span><span class="named-paragraph-number">7.1</span></a></span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP7_2" class="named-paragraph-link"><span class="named-paragraph">A value instance</span><span class="named-paragraph-number">7.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP7_1" class="paragraph-anchor"></a><b>§7.1. </b>Each instance of a kind of object becomes a VM-object:
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">An object instance</span><span class="named-paragraph-number">7.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">c</span><span class="plain-syntax"> = </span><a href="2-vo.html#SP11" class="function-link"><span class="function-syntax">VanillaObjects::spatial_depth</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">inst_s</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">is_dir</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K_direction</span><span class="plain-syntax"> =</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RunningPipelines::get_symbol</span><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">from_step</span><span class="plain-syntax">, </span><span class="identifier-syntax">direction_kind_RPSYM</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K_direction</span><span class="plain-syntax">) </span><span class="identifier-syntax">is_dir</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TypenameInstruction::is_a</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_direction</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_object_header</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">InterSymbol::trans</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">),</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">InterSymbol::trans</span><span class="plain-syntax">(</span><span class="identifier-syntax">inst_s</span><span class="plain-syntax">), </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">c</span><span class="plain-syntax">, </span><span class="identifier-syntax">is_dir</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP7">§7</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP7_2" class="paragraph-anchor"></a><b>§7.2. </b>And instances of enumerated kinds are simply declared as constant values,
equal to their enumeration numbers. So for e.g.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="identifier-syntax">Colour</span><span class="plain-syntax"> </span><span class="identifier-syntax">is</span><span class="plain-syntax"> </span><span class="identifier-syntax">a</span><span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> </span><span class="identifier-syntax">of</span><span class="plain-syntax"> </span><span class="identifier-syntax">value</span><span class="plain-syntax">. </span><span class="identifier-syntax">Red</span><span class="plain-syntax">, </span><span class="identifier-syntax">blue</span><span class="plain-syntax"> </span><span class="identifier-syntax">and</span><span class="plain-syntax"> </span><span class="identifier-syntax">green</span><span class="plain-syntax"> </span><span class="identifier-syntax">are</span><span class="plain-syntax"> </span><span class="identifier-syntax">colours</span><span class="plain-syntax">.</span>
</pre>
<p class="commentary">...we would declare the constant <span class="extract"><span class="extract-syntax">I_blue</span></span> as being equal to 2, Inform having
enumerated these colours as 1, 2, 3.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">A value instance</span><span class="named-paragraph-number">7.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">, </span><span class="string-syntax">"%d"</span><span class="plain-syntax">, </span><span class="identifier-syntax">enumeration</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg2.html#SP11" class="function-link"><span class="function-syntax">Generators::declare_constant</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">inst_s</span><span class="plain-syntax">, </span><span class="constant-syntax">RAW_GDCFORM</span><span class="plain-syntax">, </span><span class="identifier-syntax">val</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">)</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP7">§7</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>§8. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::end_instance</span><button class="popup" onclick="togglePopup('usagePopup6')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup6">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::end_instance</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">inst_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">, </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">kind_s</span><span class="plain-syntax"> == </span><span class="identifier-syntax">RunningPipelines::get_symbol</span><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">from_step</span><span class="plain-syntax">, </span><span class="identifier-syntax">object_kind_RPSYM</span><span class="plain-syntax">)) ||</span>
<span class="plain-syntax"> (</span><a href="2-vo.html#SP7" class="function-link"><span class="function-syntax">VanillaObjects::is_kind_of_object</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_s</span><span class="plain-syntax">)))</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_object_footer</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>§9. </b>For the I6 header syntax, see the DM4. Note that the "hardwired" short
name is intentionally made blank: we always use I6's <span class="extract"><span class="extract-syntax">short_name</span></span> property
instead. I7's spatial plugin, if loaded (as it usually is), will have
annotated the Inter symbol for the object with an "arrow count", that is,
a measure of its spatial depth. This we translate into I6 arrow notation.
If the spatial plugin wasn't loaded then we have no notion of containment,
all arrow counts are 0, and we define a flat sequence of free-standing objects.
</p>
<p class="commentary">One last oddball thing is that direction objects have to be compiled in I6
as if they were spatially inside a special VM-object called <span class="extract"><span class="extract-syntax">Compass</span></span>. This
doesn't really make much conceptual sense, and I7 dropped the idea — it has no
"compass".
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::VM_object_header</span><button class="popup" onclick="togglePopup('usagePopup7')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup7">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::VM_object_header</span></span>:<br/><a href="4-i6o.html#SP5_2">§5.2</a>, <a href="4-i6o.html#SP7_1">§7.1</a>, <a href="4-i6o.html#SP10">§10</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">class_name</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">instance_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">printed_name</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">acount</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">is_dir</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> *</span><span class="identifier-syntax">saved</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> *</span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">objects_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"%S"</span><span class="plain-syntax">, </span><span class="identifier-syntax">class_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">i</span><span class="plain-syntax">=0; </span><span class="identifier-syntax">i</span><span class="plain-syntax"><</span><span class="identifier-syntax">acount</span><span class="plain-syntax">; </span><span class="identifier-syntax">i</span><span class="plain-syntax">++) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" ->"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" %S"</span><span class="plain-syntax">, </span><span class="identifier-syntax">instance_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">is_dir</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" Compass"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::VM_property</span><button class="popup" onclick="togglePopup('usagePopup8')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup8">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::VM_property</span></span>:<br/><a href="4-i6o.html#SP11">§11</a>, <a href="4-i6o.html#SP12">§12</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">val</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">property_name</span><span class="plain-syntax"> = </span><a href="2-vo.html#SP3" class="function-link"><span class="function-syntax">VanillaObjects::inner_property_name</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">InterSymbol::get_flag</span><span class="plain-syntax">(</span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">ATTRIBUTE_MARK_ISYMF</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Str::eq</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"0"</span><span class="plain-syntax">)) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" has ~%S\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">property_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" has %S\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">property_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" with %S %S\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">property_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">val</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::VM_object_footer</span><button class="popup" onclick="togglePopup('usagePopup9')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup9">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::VM_object_footer</span></span>:<br/><a href="4-i6o.html#SP6">§6</a>, <a href="4-i6o.html#SP8">§8</a>, <a href="4-i6o.html#SP10">§10</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">";\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP10" class="paragraph-anchor"></a><b>§10. </b>Pseudo-objects are directly turned into VM-objects, albeit "concealed" ones.
This is used only for objects created in kits but which have no existence at
the I7 level (hence "pseudo"). <span class="extract"><span class="extract-syntax">Compass</span></span>, mentioned above, is one such; the
other one used by the standard kits supplied with Inform is <span class="extract"><span class="extract-syntax">thedark</span></span>. I urge
people to create no further pseudo-objects.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::pseudo_object</span><button class="popup" onclick="togglePopup('usagePopup10')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup10">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::pseudo_object</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">obj_name</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_object_header</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"Object"</span><span class="plain-syntax">, </span><span class="identifier-syntax">obj_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">, </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">, &</span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" \"(%S object)\"\n has concealed\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">obj_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_object_footer</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP11" class="paragraph-anchor"></a><b>§11. </b>That just leaves property values. The wrinkle here is the peculiar syntax
used for I6's inline property arrays, which look like this:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">with</span><span class="plain-syntax"> </span><span class="identifier-syntax">name</span><span class="plain-syntax"> </span><span class="character-syntax">'hoochie'</span><span class="plain-syntax"> </span><span class="character-syntax">'coochie'</span><span class="plain-syntax"> </span><span class="character-syntax">'band'</span><span class="plain-syntax">,</span>
</pre>
<p class="commentary">At the Inter level, this is represented by having the property value — i.e.
the pair <span class="extract"><span class="extract-syntax">val1</span></span>, <span class="extract"><span class="extract-syntax">val2</span></span> below — refer to a constant list containing three
entries (the three dictionary words above). But if we compiled that directly,
then an attempt to look up the property address <span class="extract"><span class="extract-syntax">obj.&name</span></span> would return the
address of the address of the array, not the address of the array itself. So
we must use the pecualiar I6 syntax here to get the right outcome.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::assign_property</span><button class="popup" onclick="togglePopup('usagePopup11')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup11">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::assign_property</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_pair</span><span class="plain-syntax"> </span><span class="identifier-syntax">pair</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">X</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP13" class="function-link"><span class="function-syntax">CodeGen::select_temporary</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">val</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">inline_this</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">InterValuePairs::is_symbolic</span><span class="plain-syntax">(</span><span class="identifier-syntax">pair</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">S</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterValuePairs::to_symbol_at</span><span class="plain-syntax">(</span><span class="identifier-syntax">pair</span><span class="plain-syntax">, </span><span class="identifier-syntax">X</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">ConstantInstruction::is_inline</span><span class="plain-syntax">(</span><span class="identifier-syntax">S</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbol::definition</span><span class="plain-syntax">(</span><span class="identifier-syntax">S</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">i</span><span class="plain-syntax">=0; </span><span class="identifier-syntax">i</span><span class="plain-syntax"><</span><span class="identifier-syntax">ConstantInstruction::list_len</span><span class="plain-syntax">(</span><span class="identifier-syntax">P</span><span class="plain-syntax">); </span><span class="identifier-syntax">i</span><span class="plain-syntax">++) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">i</span><span class="plain-syntax">>0) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" "</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP18" class="function-link"><span class="function-syntax">CodeGen::pair</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">P</span><span class="plain-syntax">, </span><span class="identifier-syntax">ConstantInstruction::list_entry</span><span class="plain-syntax">(</span><span class="identifier-syntax">P</span><span class="plain-syntax">, </span><span class="identifier-syntax">i</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inline_this</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">inline_this</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">) </span><a href="2-cg.html#SP18" class="function-link"><span class="function-syntax">CodeGen::pair</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">X</span><span class="plain-syntax">, </span><span class="identifier-syntax">pair</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP13" class="function-link"><span class="function-syntax">CodeGen::deselect_temporary</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_property</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">val</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">val</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP12" class="paragraph-anchor"></a><b>§12. </b>And this much easier function assigns a stick of property values for a property
of a value kind. (An array which is not inline.)
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::assign_properties</span><button class="popup" onclick="togglePopup('usagePopup12')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup12">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::assign_properties</span></span>:<br/><a href="4-i6o.html#SP1">§1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">array</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><a href="4-i6o.html#SP9" class="function-link"><span class="function-syntax">I6TargetObjects::VM_property</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">prop_s</span><span class="plain-syntax">, </span><span class="identifier-syntax">array</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP13" class="paragraph-anchor"></a><b>§13. A few resources. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">I6TargetObjects::end_generation</span><button class="popup" onclick="togglePopup('usagePopup13')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup13">Usage of <span class="code-font"><span class="function-syntax">I6TargetObjects::end_generation</span></span>:<br/>Generating Inform 6 - <a href="4-fi6.html#SP7">§7</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">I6_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">DebugAttribute_seen</span><span class="plain-syntax">) == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">) </span><span class="comment-syntax"> hardly ever happens</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP13_1" class="named-paragraph-link"><span class="named-paragraph">Compile a DebugAttribute function</span><span class="named-paragraph-number">13.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">I6_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">value_ranges_needed</span><span class="plain-syntax">)) </span><span class="comment-syntax"> almost always happens</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP13_2" class="named-paragraph-link"><span class="named-paragraph">Compile the value_ranges array</span><span class="named-paragraph-number">13.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">I6_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">value_property_holders_needed</span><span class="plain-syntax">)) </span><span class="comment-syntax"> almost always happens</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="4-i6o.html#SP13_3" class="named-paragraph-link"><span class="named-paragraph">Compile the value_property_holders array</span><span class="named-paragraph-number">13.3</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP13_1" class="paragraph-anchor"></a><b>§13.1. </b>I6 compiles a thin layer veneer code in addition to the source code which is
explicitly part of the program, and that code expects a function <span class="extract"><span class="extract-syntax">DebugAttribute</span></span>
to exist somewhere in the program. Now in fact BasicInformKit does define such a
function, but we want to cover ourselves against the possibility that not even
BasicInformKit is part of the Inter tree. So:
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Compile a DebugAttribute function</span><span class="named-paragraph-number">13.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">functions_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"[ DebugAttribute a anames str;\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" print \"<attribute \", a, \">\";\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"];\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP13">§13</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP13_2" class="paragraph-anchor"></a><b>§13.2. </b>Okay, so the array <span class="extract"><span class="extract-syntax">value_ranges</span></span> gives the largest valid enumeration count for
each enumerative kind, and is indexed by weak kind ID.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Compile the value_ranges array</span><span class="named-paragraph-number">13.2</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">arrays_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"Array value_ranges --> 0"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">max_weak_id</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbolsTable::URL_to_symbol</span><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">from</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">I</span><span class="string-syntax">"/main/synoptic/kinds/BASE_KIND_HWM"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">max_weak_id</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbol::evaluate_to_int</span><span class="plain-syntax">(</span><span class="identifier-syntax">max_weak_id</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">w</span><span class="plain-syntax">=1; </span><span class="identifier-syntax">w</span><span class="plain-syntax"><</span><span class="identifier-syntax">M</span><span class="plain-syntax">; </span><span class="identifier-syntax">w</span><span class="plain-syntax">++) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">written</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax">, </span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">kinds_in_declaration_order</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP6" class="function-link"><span class="function-syntax">VanillaObjects::weak_id</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">) == </span><span class="identifier-syntax">w</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP8" class="function-link"><span class="function-syntax">VanillaObjects::value_kind_with_properties</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">written</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" %d"</span><span class="plain-syntax">, </span><span class="identifier-syntax">TypenameInstruction::instance_count</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">written</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" 0"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">";\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP13">§13</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP13_3" class="paragraph-anchor"></a><b>§13.3. </b>Similarly, the array <span class="extract"><span class="extract-syntax">value_property_holders</span></span> gives the VM-object nunbers for
the value property holders for each enumerative kind.
</p>
<p class="commentary"><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Compile the value_property_holders array</span><span class="named-paragraph-number">13.3</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">arrays_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"Array value_property_holders --> 0"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">max_weak_id</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbolsTable::URL_to_symbol</span><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">from</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">I</span><span class="string-syntax">"/main/synoptic/kinds/BASE_KIND_HWM"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">max_weak_id</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">M</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbol::evaluate_to_int</span><span class="plain-syntax">(</span><span class="identifier-syntax">max_weak_id</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">for</span><span class="plain-syntax"> (</span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">w</span><span class="plain-syntax">=1; </span><span class="identifier-syntax">w</span><span class="plain-syntax"><</span><span class="identifier-syntax">M</span><span class="plain-syntax">; </span><span class="identifier-syntax">w</span><span class="plain-syntax">++) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">written</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax">, </span><span class="identifier-syntax">gen</span><span class="plain-syntax">-></span><span class="element-syntax">kinds_in_declaration_order</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP6" class="function-link"><span class="function-syntax">VanillaObjects::weak_id</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">) == </span><span class="identifier-syntax">w</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="2-vo.html#SP8" class="function-link"><span class="function-syntax">VanillaObjects::value_kind_with_properties</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind_name</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">written</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" VPH_%d"</span><span class="plain-syntax">, </span><span class="identifier-syntax">w</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">written</span><span class="plain-syntax"> == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" 0"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">";\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="4-i6o.html#SP13">§13</a>.</li></ul>
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