Member functions in Python

self.func is a operation that bind self to the function.

class A(object):
    def __init__(self):
        self.b = B()
        self.b.run(self.func)

    def func(self):
        print "callback"

class B(object):
    def run(self, cb):
        self.cb = cb
        self.cb()

import sys
foo = A()
print sys.getrefcount(foo) # output: 3

Here are 3 objects ref to foo:

• foo as a local variable,
• a ref in getrefcount
• a ref in foo.b.cb

It's more like self.func is func.self = self, bind self to the function.