Get Python function's owning class from decorator

python class function decorator inspect
Corey Coogan picture Corey Coogan · Oct 6, 2011 · Viewed 8.1k times · Source

I have a decorator in PY. It is a method and takes the function as a parameter. I want to create a directory structure based based on the passed function. I am using the module name for the parent directory but would like to use the classname for a subdirectory. I can't figure out how to get the name of the class that owns the fn object.

My Decorator:

def specialTest(fn):
    filename = fn.__name__
    directory = fn.__module__
    subdirectory = fn.__class__.__name__ #WHERE DO I GET THIS

Answer

David Wolever picture David Wolever · Oct 6, 2011

If fn is an instancemethod, then you can use fn.im_class.

>>> class Foo(object):
...     def bar(self):
...         pass
...
>>> Foo.bar.im_class
__main__.Foo

Note that this will not work from a decorator, because a function is only transformed into an instance method after the class is defined (ie, if @specialTest was used to decorate bar, it would not work; if it's even possible, doing it at that point would have to be done by inspecting the call stack or something equally unhappy).

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