Method overloading decorator

Question

I\'m trying to write a decorator that provides method overloading functionality to python, similar to the one mentioned in PEP 3124.

The decorator I wrote works grea

Answer 1

Essentially, your Overload class needs a __get__ method:

def __get__(self, obj, cls):
    # Called on access of MyClass.print_first_item.
    # We return a wrapper which calls our 
    print "get", self, obj, cls
    if obj is None:
        # a function would do some checks here, but we leave that.
        return self
    else:
        return lambda *a, **k: self(obj, *a, **k)

Why?

Well, you use your Overload object as a kind of function replacement. You want it, like a function, to represent itself in a method context with different signature.

Short explanation how method access works:

object.meth(1, 2)

gets translated to

object.__dict__['meth'].__get__(object, type(object))(1, 2)

A function's __get__() returns a method object which wraps the function by prepending the object to the parameter list (where it results in self):

realmethod = object.__dict__['meth'].__get__(object, type(object))
realmethod(1, 2)

where realmethod is a method object which knows the function to be called and the self to be given to it and calls the "real" function appropriately by transforming the call into

meth(object, 1, 2)

.

This behaviour we imitate in this new __get__ method.