Default value for optional parameter

Question

I'm making a function in python that takes an optional parameter *args . This function calls upon another function passing this optional parameter as well. However, when a certain condition applies, I want the optional parameter to have a certain default value, rather than the value passed in the function call. It is clear in the snippet of code below that simply setting a new value for *args is incorrect, but what is the correct method of doing this?

def function(arg1, arg2, *args):
    if condition:
        *args = value
    function2(*args)

Answer 1

You could identify your parameter by index in args:

def function(arg1, arg2, *args):
    if condition:
        args = list(args)
        if len(args) == 0:  # the second arg in args was not set
            args.append("first default")
        if len(args) == 1:
            args.append("second default")
    function2(*args)

But as you see - it's a little ugly. It will involve a lot of if statements in case you want to use a lot of default positional arguments. Use **kwargs if you can.

Answer 2

Apparantly *args is a list, so I had to assign it as args = [value] , instead of *args = value . That way it solved the problem.