Bind method to object runtime late binding

Question

I am aware about late bindings in loop in python, but I cant find way to solve this .

def bind_method(object, methods):

    for method in methods:
        def my_method():
            result = method()

            return result

        setattr(object, method.__name__, my_method)

def test():
    class A: pass

    def bar(): 
        return "BAR"

    def foo(): 
        return "FOO"

    a = A()
    bind_method(a, [bar, foo])

    assert a.foo() == "FOO"
    assert a.bar() == "BAR"


if __name__ == "__main__":
    test()

I tried with partial in functools but not get success :(

@AKS typo error :( correct the post – Nilesh Apr 29 '16 at 14:09 — Nilesh, Apr 29 '16 at 14:09

AKS · Accepted Answer · 2016-04-29T14:22:24.073

2

When you call a.bar() my_method is invoked and since the for loop has ended the value of method for it is the last element in methods list so you always get "FOO" as result.

To check you can add a print statement:

def my_method():
    print(method.__name__) # this will always print `foo`
    result = method()

But when I set it directly:

def bind_method(object, methods):
    for method in methods:
        setattr(object, method.__name__, method)

It does work.

Using functools.partial:

from functools import partial

def bind_method(object, methods):

    for method in methods:
        def my_method(a_method):
            print(a_method.__name__) # this print correct method name
            result = a_method()
            return result

        setattr(object, method.__name__, partial(my_method, method))

edited Apr 29 '16 at 14:22

answered Apr 29 '16 at 14:08

AKS

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Its working now, but how it works with partial? if you explain then it helps to understand this concept. – Nilesh Apr 29 '16 at 14:34
It is already explained here: [How does the functools partial work in Python?](http://stackoverflow.com/questions/15331726/how-does-the-functools-partial-work-in-python) – AKS Apr 29 '16 at 14:46

Bind method to object runtime late binding

1 Answers1