[Python-Dev] [Python-checkins] r86566 - in python/branches/py3k: Doc/glossary.rst Doc/library/inspect.rst Lib/inspect.py Lib/test/test_inspect.py Misc/NEWS Misc/python-wing4.wpr

[Michael Foord]

On 20/11/2010 15:21, Nick Coghlan wrote:
> On Sun, Nov 21, 2010 at 1:07 AM, michael.foord
> <python-checkins at python.org>  wrote:
>> +Fetching attributes statically
>> +------------------------------
>> +
>> +Both :func:`getattr` and :func:`hasattr` can trigger code execution when
>> +fetching or checking for the existence of attributes. Descriptors, like
>> +properties, will be invoked and :meth:`__getattr__` and :meth:`__getattribute__`
>> +may be called.
>> +
>> +For cases where you want passive introspection, like documentation tools, this
>> +can be inconvenient. `getattr_static` has the same signature as :func:`getattr`
>> +but avoids executing code when it fetches attributes.
> This description feels a little strong to me - getattr_static still
> executes all those things on the metaclass as it retrieves the
> information it needs to do the "static" lookup. Leaving this original
> description (which assumes metaclass=type) alone and adding a note
> near the end of the section to say that metaclass code is still
> executed might be an improvement.
Can you give an example of code in a metaclass that may be executed by 
getattr_static? It's not that I don't believe you I just can't think of 
an example. Looking up the class and the mro are the only two examples I 
can think of (klass.__mro__ and instance.__class__ - and they are noted 
in the docs?) but aren't metaclass specific.

Michael

> Cheers,
> Nick.
>


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