At 08:58 PM 8/25/2010 +0300, Michael Foord wrote:
If your proxy class defines __call__ then callable returns True,
even if the delegation to the proxied object would cause an
AttributeError to be raised.
Nope. You just have to use delegate via __getattribute__ (since 2.2)
instead of __getattr__:
>>> from peak.util.proxies import ObjectProxy
>>> o=ObjectProxy(lambda:1)
>>> o()
1
>>> o.__call__
<method-wrapper '__call__' of function object at 0x00E004B0>
>>> o=ObjectProxy(1)
>>> o()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File
"c:\cygwin\home\pje\projects\proxytypes\peak\util\proxies.py", line 6, in
__call__
return self.__subject__(*args,**kw)
TypeError: 'int' object is not callable
>>> o.__call__
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File
"c:\cygwin\home\pje\projects\proxytypes\peak\util\proxies.py", line 12, i
n __getattribute__
return getattr(subject,attr)
AttributeError: 'int' object has no attribute '__call__'
As you can see, the __call__ attribute in each case is whatever the
proxied object's __call__ attribute is, even though the proxy itself
has a __call__ method, that is invoked when the proxy is called.
This is actually pretty straightforward stuff since the introduction
of __getattribute__.
(The code is at http://pypi.python.org/pypi/ProxyTypes, btw.)
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