Question

The accepted paradigm to deal with mutable default arguments is:

def func(self, a = None):
    if a is None:
        a = <some_initialisation>
    self.a = a

As I might have to do this for several arguments, I would need to write very similar 3 lines over and over again. I find this un-pythonically a lot of text to read for a very very standard thing to do when initialising class objects or functions.

Isn’t there an elegant one-liner to replace those 3 lines dealing with the potentially undefined argument and the standard required copying to the class instance variables?

Answer 1

If a “falsy” value (0, empty string, list, dict, etc.) is not a valid value for a, then you can cut down the initialization to one line:

a = a or <initialize_object>