--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/dispatch/robustapply.py	Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,47 @@
+"""Robust apply mechanism
+
+Provides a function "call", which can sort out
+what arguments a given callable object can take,
+and subset the given arguments to match only
+those which are acceptable.
+"""
+
+def function( receiver ):
+    """Get function-like callable object for given receiver
+
+    returns (function_or_method, codeObject, fromMethod)
+
+    If fromMethod is true, then the callable already
+    has its first argument bound
+    """
+    if hasattr(receiver, '__call__'):
+        # receiver is a class instance; assume it is callable.
+        # Reassign receiver to the actual method that will be called.
+        if hasattr( receiver.__call__, 'im_func') or hasattr( receiver.__call__, 'im_code'):
+            receiver = receiver.__call__
+    if hasattr( receiver, 'im_func' ):
+        # an instance-method...
+        return receiver, receiver.im_func.func_code, 1
+    elif not hasattr( receiver, 'func_code'):
+        raise ValueError('unknown reciever type %s %s'%(receiver, type(receiver)))
+    return receiver, receiver.func_code, 0
+
+def robustApply(receiver, *arguments, **named):
+    """Call receiver with arguments and an appropriate subset of named
+    """
+    receiver, codeObject, startIndex = function( receiver )
+    acceptable = codeObject.co_varnames[startIndex+len(arguments):codeObject.co_argcount]
+    for name in codeObject.co_varnames[startIndex:startIndex+len(arguments)]:
+        if named.has_key( name ):
+            raise TypeError(
+                """Argument %r specified both positionally and as a keyword for calling %r"""% (
+                    name, receiver,
+                )
+            )
+    if not (codeObject.co_flags & 8):
+        # fc does not have a **kwds type parameter, therefore 
+        # remove unacceptable arguments.
+        for arg in named.keys():
+            if arg not in acceptable:
+                del named[arg]
+    return receiver(*arguments, **named)