[Checkins] SVN: Sandbox/malthe/chameleon.zpt/ Tags are now omitted if tal:content expression evaluates to None.

[Malthe Borch]

Log message for revision 92089:
  Tags are now omitted if tal:content expression evaluates to None.

Changed:
  U   Sandbox/malthe/chameleon.zpt/CHANGES.txt
  U   Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.py
  U   Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.txt

-=-
Modified: Sandbox/malthe/chameleon.zpt/CHANGES.txt
===================================================================
--- Sandbox/malthe/chameleon.zpt/CHANGES.txt	2008-10-13 02:48:35 UTC (rev 92088)
+++ Sandbox/malthe/chameleon.zpt/CHANGES.txt	2008-10-13 02:52:16 UTC (rev 92089)
@@ -4,6 +4,11 @@
 Head
 ~~~~
 
+- Tags are now omitted if a "tal:content" expression evaluates to
+  ``None``. This behavior differs from the reference implementation,
+  but does away with the need for a similar "tal:condition"
+  attribute. [malthe]
+
 1.0a2 (released 10/2/2008)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 

Modified: Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.py
===================================================================
--- Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.py	2008-10-13 02:48:35 UTC (rev 92088)
+++ Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.py	2008-10-13 02:52:16 UTC (rev 92089)
@@ -18,6 +18,8 @@
     """
 
     class node(translation.Node):
+        content_symbol = '_content'
+        
         @property
         def omit(self):
             if self.element.tal_omit is not None:
@@ -28,12 +30,24 @@
                 return True
             if self.element.metal_use or self.element.metal_fillslot:
                 return True
-            
+            if self.content is not None:
+                return types.parts(
+                    (types.value("%s is None" % self.content_symbol),))
+
         @property
         def define(self):
             return self.element.tal_define
 
         @property
+        def assign(self):
+            content = self._content
+            if content is not None:
+                definition = (
+                    types.declaration((self.content_symbol,)),
+                    content)
+                return types.definitions((definition,))
+
+        @property
         def condition(self):
             return self.element.tal_condition
 
@@ -43,9 +57,18 @@
 
         @property
         def content(self):
-            return self.element.tal_content or self.element.tal_replace or \
+            content = self._content
+            if content is not None:
+                if isinstance(content, types.escape):
+                    return types.escape((types.value(self.content_symbol),))
+                return types.parts((types.value(self.content_symbol),))
+        
+        @property
+        def _content(self):
+            return self.element.tal_content or \
+                   self.element.tal_replace or \
                    self.element.meta_replace
-
+                    
         @property
         def skip(self):
             if self.define_slot:

Modified: Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.txt
===================================================================
--- Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.txt	2008-10-13 02:48:35 UTC (rev 92088)
+++ Sandbox/malthe/chameleon.zpt/src/chameleon/zpt/language.txt	2008-10-13 02:52:16 UTC (rev 92089)
@@ -17,7 +17,7 @@
     Hello, world!
   <BLANKLINE>
 
-tal:define, tal:attributes, tal:contents    
+tal:define, tal:attributes, tal:content, tal:replace
   
   >>> print render("""\
   ... <div xmlns="http://www.w3.org/1999/xhtml"
@@ -36,7 +36,6 @@
       <span class="defabc" style="hij" onclick="alert();" id="test">abcghi</span>
       Hello World!
       Hello World!
-      <span></span>
     </div>
 
 tal:attributes 'checked' and 'selected' toggles