Legacy from 1.0: clarify how syntactic shortcut for options are used with non-string option values

[xml-project]

clarify how syntactic shortcut for options are used with non-string option values 

This is an aggregation of the discussion on "clarify how syntactic shortcut for options are used with non-string option values" (Issue 161 of the xproc/1.0-specification)

Opened by: rdeltour on 2015-05-27, 16:12h

rdeltour said on 2015-05-27, 16:12h:

Section 4.8.1 Syntactic shortcut for options seems clear enough for atomic types, at leastxs:string, but it's unclear how to define more exoticly-typed options, like maps. 

See also#146. 

rdeltour said on 2015-05-27, 16:25h:

For a map, am I correct assuming you'd have to use an AVT in this case? 

<ex:stepType map-option="{map
	{"Su":"Sunday",
	"Mo":"Monday",
	"Tu":"Tuesday",
	"We":"Wednesday",
	"Th":"Thursday",
	"Fr":"Friday",
	"Sa":"Saturday"}}"/>

But for "castable" option value, e.g.xs:integers, is the following possible? 

<ex:stepType int-option="1"/>

Or should it be interpreted as "a non-string value can only be set with AVT"? 

ndw said on 2015-06-06, 10:17h:

You're right, some clarity is required. I think there are two possibilities. 

I have a slight preference for the former, but in the interest of backwards compatibility (and compatibility with attribute values on other elements), I think we should probably do the latter. 

rdeltour said on 2015-06-06, 11:51h:

Backwards compatibility is a compelling argument, so let's assume the value is a string. The next thing to clarify is whether any kind of type coercion is performed by the processor. For this latter, again two possibilities: 

• only xs:stringoptions can be set that way 

• type coercion is performed to set options of type xs:string, xs:boolean, xs:double, xs:integer, ???

ndw said on 2015-06-12, 10:37h:

Proposal: 

<ex:step opt="3"> 

Sets opt = string value 3. 

<ex:step opt="^3"> 

Sets opt = integer value 3 (or decimal or whatever XPath does with the expression 3) 

<ex:step opt='^map{"one": 1, "two": 2}'> 

Sets opt = a map with two keys. 

Yes, we're inventing a new escaping mechanism. 

P.S. If you want a literal ^, you have to escape itopt="^'^'" 

On 2015-06-12, 10:37h: ndw added the proposed-resolution label.

ndw said on 2015-06-12, 11:13h:

See also #80 for the questions of coercion. 

On 2015-10-07, 14:28h: ndw added this to the XProc 2.0 Next PWD milestone.

[ndw]

Doesn't seem to be an issue here. The value of the AVT is the value of the option. If the option specifies a type (using as=), the value is cast to that type, which either succeeds or fails.