richard@bizarsoftware.com.au wrote:
A simple enough scenario: Python 1.5.2 (#1, Sep 30 2000, 18:08:36) [GCC 2.95.3 19991030 (prerelease)] on linux-i386 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
import ExtensionClass import Acquisition class A(ExtensionClass.Base): ... def foo(self): ... print repr(self), type(self) ... class B(Acquisition.Implicit): ... pass ... a=A() print repr(a), type(a) <A instance at 80ec588> <extension class __main__.A at 80eb1e0> a.b=B() print repr(a.b), type(a.b) <B instance at 80dc9c0> <extension class Acquisition.ImplicitAcquirerWrapper at 401460e0> a.b.foo() <A instance at 80ec588> <extension class __main__.A at 80eb1e0>
Now, I would've expected to see a.b.foo() print out exactly the same information as repr(a.b), type(a.b). In fact, I even scrounged up the Acquisition doc (it really isn't that easy to find these days...) and I can quote from it in support of what I believe should be happening:
''' Acquisition and methods
Python methods of objects that support acquisition can use acquired attributes as in the 'report' method of the first example above. When a Python method is called on an object that is wrapped by an acquisition wrapper, the wrapper is passed to the method as the first argument. This rule also applies to user-defined method types and to C methods defined in pure mix-in classes. '''
OK, I figured it out. The method foo requires an instance of A to work, and a.b isn't one, but a is. Makes life a little more difficult, but at least we know how it works now. Richard -- Richard Jones richard@bizarsoftware.com.au Senior Software Developer, Bizar Software (www.bizarsoftware.com.au)