[FIXED] Using *args and keywords in function definition causes error

Issue

I have a function definition as follows:

def test(self, *args, wires=None, do_queue=True):
    pass

In Python3, this runs normally, but in Python2 it crashes with a SyntaxError. How can I modify it to work in Python2?

Solution

The only way to make this work in Python 2 is to accept your keyword-only arguments as **kwargs and extract them manually. Python 2 has no ability to do keyword-only arguments in any other manner; it was a new feature of Python 3 to allow this at all.

The closest Python 2 equivalent would be:

def test(self, *args, **kwargs):
    wires = kwargs.pop('wires', None)
    do_queue = kwargs.pop('do_queue', True)
    if kwargs:
        raise TypeError("test got unexpected keyword arguments: {}".format(kwargs.keys()))

Answered By - ShadowRanger