Thomas Lotze wrote:
> Apparently, when applied to a class instance, hasattr calls getattr and
> decides that the attribute doesn't exist if the call raises any exception.
> - Wouldn't it make sense to only report a missing attribute if an
> AttributeError is raised?
That would be an improvement, but calling the property access
code as a side effect of hasattr seems like a misfeature to me
in the first place.
> - As far as properties are concerned, it would make even more sense to not
> call getattr but try to look up the attribute the same way getattr would.
> This would, however, not work consistently anymore if one customizes
> attribute access.
Maybe descriptors need a fourth slot for hasattr
customisation?
The logic would then be
if there is a descriptor for the attribute:
if the descriptor's hasattr slot is populated:
return the result of calling it
else:
return True
else:
look in the instance dict for the attribute
There wouldn't be a need to rely on catching exceptions
at all, then.
--
Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury, | A citizen of NewZealandCorp, a |
Christchurch, New Zealand | wholly-owned subsidiary of USA Inc. |
greg.ewing at canterbury.ac.nz +--------------------------------------+
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