[Checkins] SVN: megrok.chameleon/branches/ulif-z3c.pt-less/src/megrok/chameleon/namespaces.py Copy over namespace handlers from z3c.pt

[Uli Fouquet]

Log message for revision 109547:
  Copy over namespace handlers from z3c.pt

Changed:
  A   megrok.chameleon/branches/ulif-z3c.pt-less/src/megrok/chameleon/namespaces.py

-=-
Copied: megrok.chameleon/branches/ulif-z3c.pt-less/src/megrok/chameleon/namespaces.py (from rev 109546, z3c.pt/trunk/src/z3c/pt/namespaces.py)
===================================================================
--- megrok.chameleon/branches/ulif-z3c.pt-less/src/megrok/chameleon/namespaces.py	                        (rev 0)
+++ megrok.chameleon/branches/ulif-z3c.pt-less/src/megrok/chameleon/namespaces.py	2010-03-02 00:54:55 UTC (rev 109547)
@@ -0,0 +1,94 @@
+import zope.component
+from zope.traversing.interfaces import IPathAdapter
+
+class AdapterNamespaces(object):
+    """Simulate tales function namespaces with adapter lookup.
+
+    When we are asked for a namespace, we return an object that
+    actually computes an adapter when called:
+
+    To demonstrate this, we need to register an adapter:
+
+      >>> def adapter1(ob):
+      ...     return 1
+      >>> zope.component.getGlobalSiteManager().registerAdapter(
+      ...     adapter1, [zope.interface.Interface], IPathAdapter, 'a1')
+
+    Now, with this adapter in place, we can try out the namespaces:
+
+      >>> ob = object()
+      >>> namespaces = AdapterNamespaces()
+      >>> namespace = namespaces['a1']
+      >>> namespace(ob)
+      1
+      >>> namespace = namespaces['a2']
+      >>> namespace(ob)
+      Traceback (most recent call last):
+      ...
+      KeyError: 'a2'
+    """
+
+    def __init__(self):
+        self.namespaces = {}
+
+    def __getitem__(self, name):
+        namespace = self.namespaces.get(name)
+        if namespace is None:
+            def namespace(object):
+                try:
+                    return zope.component.getAdapter(object, IPathAdapter, name)
+                except zope.component.ComponentLookupError:
+                    raise KeyError(name)
+
+            self.namespaces[name] = namespace
+        return namespace
+
+
+    def registerFunctionNamespace(self, namespacename, namespacecallable):
+        """Register a function namespace
+
+        namespace - a string containing the name of the namespace to
+                    be registered
+
+        namespacecallable - a callable object which takes the following
+                            parameter:
+
+                            context - the object on which the functions
+                                      provided by this namespace will
+                                      be called
+
+                            This callable should return an object which
+                            can be traversed to get the functions provided
+                            by the this namespace.
+
+        example:
+
+           class stringFuncs(object):
+
+              def __init__(self,context):
+                 self.context = str(context)
+
+              def upper(self):
+                 return self.context.upper()
+
+              def lower(self):
+                 return self.context.lower()
+
+            engine.registerFunctionNamespace('string',stringFuncs)
+        """
+        self.namespaces[namespacename] = namespacecallable
+
+
+    def getFunctionNamespace(self, namespacename):
+        """ Returns the function namespace """
+        return self.namespaces[namespacename]
+
+try:
+    # If zope.app.pagetemplates is available, use the adapter
+    # registered with the main zope.app.pagetemplates engine so that
+    # we don't need to re-register them.
+    from zope.app.pagetemplates.engine import Engine
+    function_namespaces = Engine.namespaces
+except (ImportError, AttributeError):
+    function_namespaces = AdapterNamespaces()
+