CODEWITHSUNDEEP
python
Carsten
Carsten

Reputation: 4334

Python: Test if x is a particular method object

I have a python function that looks roughly like this:

def f(x):
    [...]
    g(x)

Sometimes, for reasons beyond my control x is of type <bound method A.b of <A: a>> . g() is in a 3rd party library and can not handle this argument and throws an exception. So what I want to do before g() is called is to test for this case and do something else instead:

def f(x):
    [...]
    if x == A.b:
       doSometingElse()
    else:
       g(x)

Now, == does not seem to work as it is never true. What is the correct way to test if my variable x contains the method A.b?

Upvotes: 0

Views: 95

Answers (2)

Ned Batchelder
Ned Batchelder

Reputation: 376052

The function in the class is turned into a bound method when accessed on an object, or an unbound method when accessed on the class. In Python 2, both types have a func attribute that refer to the function. So your test could look like:

if x.__func__ is A.b.__func__:

In Python 3 it's a little easier:

if x.__func__ is A.b:

Upvotes: 2

Ashiro
Ashiro

Reputation: 44

Maybe try to throw a try except in there

def f(x):
    [...]
    try:
        g(x)
    except:
        do something else

this would be the easiest way to handle it.

Upvotes: -1

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