Python 3 Object-Oriented Programming - Third Edition

Unpacking arguments

There's one more nifty trick involving variable arguments and keyword arguments. We've used it in some of our previous examples, but it's never too late for an explanation. Given a list or dictionary of values, we can pass those values into a function as if they were normal positional or keyword arguments. Have a look at this code:

def show_args(arg1, arg2, arg3="THREE"): 
    print(arg1, arg2, arg3) 
 
some_args = range(3) 
more_args = { 
        "arg1": "ONE", 
        "arg2": "TWO"} 
 
print("Unpacking a sequence:", end=" ") 
 
show_args(*some_args) 
print("Unpacking a dict:", end=" ") 
 
show_args(**more_args) 

Here's what it looks like when we run it:

Unpacking a sequence: 0 1 2
Unpacking a dict: ONE TWO THREE  

The function accepts three arguments, one ...