CODEWITHSUNDEEP
python
David Mulder
David Mulder

Reputation: 8027

Python not defined error when using with block

class fcount(object):
    def __init__(self, func):
            self.func = func
            self.count = 0
            self.context_count = 0
    def __enter__(self):
            self.context_count = 0
    def __call__(self, *args):
            self.count += 1
            self.context_count += 1
            return self.func(*args)
    def __exit__(self, exctype, value, tb):
            return False

This is a decorator. The idea is to keep a separate count when using a 'with' block.

If I do this:

@fcount
def f(n):
    return n+2

with fcount(foo) as g:
    print g(1)

I get this error: TypeError: 'NoneType' object is not callable

I tried printing out the type of g inside that with block, and of course the type is None.

Any idea why g isn't being assigned to fcount(foo)?

This does work:

g = fcount(foo)
with g:
    g(1)

Upvotes: 2

Views: 85

Answers (1)

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 798716

You forgot to return the object from __enter__().

Upvotes: 2

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