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.)