[Zope-Checkins] CVS: Zope3/lib/python/Zope/App/Traversing - __init__.py:1.1.2.2

[Steve Alexander]

Update of /cvs-repository/Zope3/lib/python/Zope/App/Traversing
In directory cvs.zope.org:/tmp/cvs-serv12579

Modified Files:
      Tag: Zope-3x-branch
	__init__.py 
Log Message:
Added a ZopeWrapper function that is responsible for wrapping
objects except None + primitive types in a ContextWrapper.Wrapper.

Also, hack __builtins__.isinstance to look at obj.__class__ for
types and new-style classes. This hack to remain until Python
impements this feature.


=== Zope3/lib/python/Zope/App/Traversing/__init__.py 1.1.2.1 => 1.1.2.2 ===
 """
 
+from Zope.ContextWrapper import Wrapper
+def ZopeWrapper(obj, context):
+    if obj is None or isinstance(obj,
+        (int, long, float, complex, unicode, str)):
+        return obj
+    return Wrapper(obj, context)
+    
+del Wrapper
+
+
+# hack isinstance in __builtins__ to respect __class__ of new-style
+# classes and of types.
+# this hack to remain until this feature is present in Python 2.2
+#
+# do this lazily by only trying comparison on __class__ if standard
+# isinstance returns 0
+def isinstance(obj, class_or_type_or_tuple, isinstance=isinstance):
+    result = isinstance(obj, class_or_type_or_tuple)
+    if result:
+        return 1
+        
+    # otherwise compare on __class__
+    cls = getattr(obj, '__class__', None)
+    if cls is None:
+        return 0
+    
+    # talks advantage of cls in nested scope
+    def flatten(arg):
+        if isinstance(arg, tuple):
+            for t in arg:
+                if flatten(t):
+                    return 1
+            return 0
+        else:
+            return issubclass(cls, arg)
+
+    return flatten(class_or_type_or_tuple)
+    
+__builtins__.isinstance = isinstance
+del isinstance
+
+# borrow the Python tests, and add some to test our new behaviour
+
+from test.test_support import TestFailed
+
+class C:
+    pass
+class D(C):
+    pass
+class E:
+    pass
+c = C()
+d = D()
+e = E()
+if not isinstance(c, C): raise TestFailed, 'isinstance(c, C)'
+if not isinstance(d, C): raise TestFailed, 'isinstance(d, C)'
+if isinstance(e, C): raise TestFailed, 'isinstance(e, C)'
+if isinstance(c, D): raise TestFailed, 'isinstance(c, D)'
+if isinstance('foo', E): raise TestFailed, 'isinstance("Foo", E)'
+try:
+    isinstance(E, 'foo')
+    raise TestFailed, 'isinstance(E, "foo")'
+except TypeError:
+    pass
+
+from Zope.ContextWrapper import Wrapper
+class C:
+    pass
+class D(C):
+    pass
+class E:
+    pass
+c = Wrapper(C())
+d = Wrapper(D())
+e = Wrapper(E())
+if not isinstance(c, (C, int, int, (int, int, (int,)))):
+    raise TestFailed, 'isinstance(c, C)'
+if not isinstance(d, C): raise TestFailed, 'isinstance(d, C)'
+if isinstance(e, C): raise TestFailed, 'isinstance(e, C)'
+if isinstance(c, D): raise TestFailed, 'isinstance(c, D)'
+if isinstance('foo', E): raise TestFailed, 'isinstance("Foo", E)'
+try:
+    isinstance(E, 'foo')
+    raise TestFailed, 'isinstance(E, "foo")'
+except TypeError:
+    pass
+    
+del TestFailed