Monkeypatching a staticmethod?

Roy Smith roy at panix.com
Fri Jan 10 00:23:11 EST 2014


This is kind of surprising.  I'm running Python 2.7.1.  I've got a class 
with a staticmethod that I want to monkeypatch with a lambda:

----------------------------------
class Foo:
    @staticmethod
    def x():
        return 1

Foo.x = lambda: 2
print Foo.x()
----------------------------------

What's weird is that it seems to remember that x is a staticmethod 
despite having been patched:

Traceback (most recent call last):
  File "static.py", line 8, in <module>
    Foo.x()
TypeError: unbound method <lambda>() must be called with Foo instance as 
first argument (got nothing instead)

What seems to work is to patch it with another staticmethod:

----------------------------------
class Foo:
    @staticmethod
    def x():
        return 1

@staticmethod
def x():
    return 2

Foo.x = x
print Foo.x()
----------------------------------

$ python static.py
2

I didn't even know you could define a staticmethod outside of a class!

I suspect this post is really just my way of admitting that while I've 
used staticmethods plenty, I've never fully understood the details of 
what happens when you construct them :-)



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