[Python-Dev] Re: Confusing "hasattr" behaviour
tjreedy at udel.edu
Thu Feb 24 22:25:07 CET 2005
"J. David Ibanez" <jdavid at itaapy.com> wrote in message
news:421B8C4B.5050003 at itaapy.com...
Given that the behavior of hasattr is clearly defined in Lib Manual 2.1 as
def hasattr(obj, name):
I am not sure what could be confusing about it. It is a simple getattr
wrapper converting 'got something' to True and 'did not get anything'
(raised an exception instead) to False. Users should know this so they
don't wastefully write 'if hasattr(o,n): x = getattr(o,n)'
>Today I have spent a while to hunt down a couple of bugs in my
>because "hasattr" was catching the exceptions.
If you want a different behavior, you can write your own version now,
without waiting for a future that may never come, that only converts
AttributeError to False and that possibly collapses all others to one type
of your choosing. To make sure that even this does not mask a bug, one
needs to make sure that .__getattr__ methods do not pass on unintended
Terry J. Reedy
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