Require braces for interpolation expression everywhere except inside …

…the ``string:`` expression type.
malthe · Jul 25, 2011 · b5a2160 · b5a2160
1 parent 9c5bb74
commit b5a2160
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Showing 13 changed files with 46 additions and 17 deletions.
diff --git a/CHANGES.rst b/CHANGES.rst
@@ -1,6 +1,18 @@
 Changes
 =======
 
+In next release...
+
+Features:
+
+- Expression interpolation (using the ``${...}`` operator and
+  previously also ``$identifier``) now requires braces everywhere
+  except inside the ``string:`` expression type.
+
+  This change is motivated by a number of legacy templates in which
+  the interpolation format without braces ``$identifier`` appears as
+  text.
+
 2.0.2 (2011-07-25)
 ------------------
 

diff --git a/docs/reference.rst b/docs/reference.rst
@@ -1406,9 +1406,6 @@ included in the output (all inserted text is escaped by default):
     ${content}
   </div>
 
-Note that to insert the value of a symbol, the curly braces can be
-omitted entirely: ``Hello, $name!``.
-
 To escape this behavior, prefix the notation with a backslash
 character: ``\${...}``.
 

diff --git a/src/chameleon/compiler.py b/src/chameleon/compiler.py
@@ -337,7 +337,7 @@ def engine(expression, target):
             node = Expression(expression)
             return self.translate(node, target)
 
-        expression = StringExpr(node.value)
+        expression = StringExpr(node.value, node.braces_required)
         return expression(target, engine)
 
     def visit_Translate(self, node, target):
@@ -583,7 +583,7 @@ def engine(expression, target):
             return self._engine(node, target) + \
                    convert(target)
 
-        expression = StringExpr(node.value)
+        expression = StringExpr(node.value, node.braces_required)
 
         name = identifier("content")
 

diff --git a/src/chameleon/nodes.py b/src/chameleon/nodes.py
@@ -139,7 +139,7 @@ class Text(Node):
 class Interpolation(Text):
     """String interpolation output."""
 
-    _fields = "value", "escape"
+    _fields = "value", "escape", "braces_required"
 
 
 class Translate(Node):

diff --git a/src/chameleon/tales.py b/src/chameleon/tales.py
@@ -337,6 +337,17 @@ class StringExpr(object):
     >>> test(StringExpr('Hello ${world}!'))
     'Hello world!'
 
+    In the default configuration, braces may be omitted if the
+    expression is an identifier.
+
+    >>> test(StringExpr('Hello $world!'))
+    'Hello world!'
+
+    The ``braces_required`` flag changes this setting:
+
+    >>> test(StringExpr('Hello $world!', True))
+    'Hello $world!'
+
     We can escape interpolation using the standard escaping
     syntax:
 
@@ -382,15 +393,20 @@ class StringExpr(object):
     'There are 11 characters in \"hello world\"'
     """
 
-    regex = re.compile(
+    braces_required_regex = re.compile(
+        r'(?<!\\)\$({(?P<expression>.*)})')
+
+    braces_optional_regex = re.compile(
         r'(?<!\\)\$({(?P<expression>.*)}|(?P<variable>[A-Za-z][A-Za-z0-9_]*))')
 
-    def __init__(self, expression):
+    def __init__(self, expression, braces_required=False):
         # The code relies on the expression being a token string
         if not isinstance(expression, Token):
             expression = Token(expression, 0)
 
         self.expression = expression
+        self.regex = self.braces_required_regex if braces_required else \
+                     self.braces_optional_regex
 
     def __call__(self, name, engine):
         """The strategy is to find possible expression strings and

diff --git a/src/chameleon/tests/inputs/001-variable-scope.pt b/src/chameleon/tests/inputs/001-variable-scope.pt
@@ -1,7 +1,6 @@
 <html>
   <body tal:define="text 'Hello world!'">
     ${text}
-    $text
   </body>
   <tal:check condition="exists: text">
     bad

diff --git a/src/chameleon/tests/inputs/006-attribute-interpolation.pt b/src/chameleon/tests/inputs/006-attribute-interpolation.pt
@@ -1,6 +1,8 @@
 <html>
-  <body class="ltr">
+  <body class="ltr" tal:define="hash string:#">
     <img src="${'#'}" alt="copyright (c) ${2010}" />
-    <img src="${None}" />
+    <img src="" alt="copyright (c) ${2010}" tal:attributes="src string:$hash" />
+    <img src="" alt="copyright (c) ${2010}" tal:attributes="src string:${hash}" />
+    <img src="${None}" alt="$ignored" />
   </body>
 </html>
diff --git a/src/chameleon/tests/inputs/007-content-interpolation.pt b/src/chameleon/tests/inputs/007-content-interpolation.pt
@@ -3,6 +3,7 @@
     ${'Hello world!'}
     ${literal}
     ${None}
+    $leftalone
     <div>${None}</div>
   </body>
 </html>
diff --git a/src/chameleon/tests/inputs/063-continuation.pt b/src/chameleon/tests/inputs/063-continuation.pt
@@ -1,4 +1,4 @@
 <div tal:define="foo 1 + \
                      1">
-  $foo
+  ${foo}
 </div>
diff --git a/src/chameleon/tests/outputs/001.pt b/src/chameleon/tests/outputs/001.pt
@@ -1,7 +1,6 @@
 <html>
   <body>
     Hello world!
-    Hello world!
   </body>
 
 

diff --git a/src/chameleon/tests/outputs/006.pt b/src/chameleon/tests/outputs/006.pt
@@ -1,6 +1,8 @@
 <html>
   <body class="ltr">
     <img src="#" alt="copyright (c) 2010" />
-    <img />
+    <img src="#" alt="copyright (c) 2010" />
+    <img src="#" alt="copyright (c) 2010" />
+    <img alt="$ignored" />
   </body>
 </html>
diff --git a/src/chameleon/tests/outputs/007.pt b/src/chameleon/tests/outputs/007.pt
@@ -3,6 +3,7 @@
     Hello world!
     <div>Hello world!</div>
 
+    $leftalone
     <div></div>
   </body>
 </html>
diff --git a/src/chameleon/zpt/program.py b/src/chameleon/zpt/program.py
@@ -476,7 +476,7 @@ def visit_comment(self, node):
         if self._interpolation[-1]:
             return nodes.Sequence(
                 [nodes.Text(node[:4]),
-                 nodes.Interpolation(node[4:-3], self._escape),
+                 nodes.Interpolation(node[4:-3], self._escape, True),
                  nodes.Text(node[-3:])
                  ])
 
@@ -486,7 +486,7 @@ def visit_text(self, node):
         self._last = node
 
         if self._interpolation_enabled:
-            return nodes.Interpolation(node, self._escape)
+            return nodes.Interpolation(node, self._escape, True)
 
         return nodes.Text(node)
 
@@ -543,7 +543,7 @@ def _create_attributes_nodes(self, prepared, I18N_ATTRIBUTES):
             # more interpolation expressions, make the attribute
             # dynamic
             if expr is None and text is not None and '${' in text:
-                value = nodes.Interpolation(text, True)
+                value = nodes.Interpolation(text, True, True)
 
             # If this expression is non-trivial, the attribute is
             # dynamic (computed)