Any ideas about the best work around for __new__ losing its arguments?

Question

So, I only realised today that __new__ is deprecated for receiving arguments, as of python 2.6 (it isn\'t mentioned in the documentation, which is also not true

Answer 1

Well this made me curious because I did not see the deprecation in the documentation so I gave it a try myself.

class Foo(object):
    def __new__(cls, a, b):
        if a:
            return a
        elif b:
            return b
        else:
            return super(Foo, cls).__new__(cls, a, b)

    def __init__(self, a, b):
        self.a = a
        self.b = b

class Bar(Foo):
    def __new__(cls, x, y):
        if x:
            return x
        if y:
            return y
        else:
            return super(Bar, cls).__new__(cls, x, y)


foo = Bar(False, False)

As you can see in this example I overrode the init in Foo because any args passed to new will be forwarded to the cls instance that __new__ attempts to create. The instance of foo with be of a Bar class but it will have members a and b. I caused the super class's __init__ to be called by not overriding it. The method __new__ always passes its args on to __init__. If you don't override the __init__ for object it will fail since that method takes no args.

That's my take on the usage of new in Python 2.7. According to the docs 2.6 is similar.