[Python-Dev] update_wrapper should preserve staticmethod behavior

[Guido van Rossum]

Please submit a fix to the issue tracker at bugs.python.org if you
care about this.

On Wed, Jun 11, 2008 at 7:06 AM, Calvin Spealman
<ironfroggy at socialserve.com> wrote:
> I'd like to make a claim about the following example, that update_wrapper
> should be improved to preserve the behavior of known, built-in decorators.
> In this case, I'm talking about staticmethod. The order I list here feels
> natural, but it obviously doesn't work. The only reason it doesn't seems to
> be that it is trying to decorate the descriptor, not the function itself.
> This is expected, but it could certainly be smart enough to detect a
> descriptor and attempt to get the actual callable underneath, could it not?
> It would not work for all cases, of course.
>
>>>> def d(f):
> ...     def nf(*a, **kw):
> ...             print "decorated function called"
> ...             return f(*a, **kwargs)
> ...     functools.update_wrapper(nf, f)
> ...     return nf
> ...
>>>> class A(object):
> ...     @d
> ...     @staticmethod
> ...     def a(self):
> ...             print "a"
> ...
> Traceback (most recent call last):
>  File "<stdin>", line 1, in <module>
>  File "<stdin>", line 3, in A
>  File "<stdin>", line 5, in d
>  File
> "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/functools.py",
> line 33, in update_wrapper
>    setattr(wrapper, attr, getattr(wrapped, attr))
> AttributeError: 'staticmethod' object has no attribute '__module__'
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--Guido van Rossum (home page: http://www.python.org/~guido/)