Keyword arguments

What

Keyword arguments explicitly match arguments to parameters using the parameters’ identifiers.

Why

Using keyword arguments makes longer function calls more readable by explicitly naming the parameters and assigning their values.

Additionally, keyword arguments match by identifier rather than position. Keyword arguments do not change whether an argument is required or not, they just give flexibility with the ordering of arguments when writing subprogram calls.

The flexibility of ordering enabled by keyword arguments is extremely helpful when using default parameters as it allows their use irrespective of position.

Examples

Parameter order

If you use keyword arguments for all the arguments in the subprogram call, the order does not matter at all.

def create_username(forename, surname, year):
    username = f"{forename[0]}{surname}{year[2:]}"
    return username
 
user = create_username(forename="Jon", surname="Hamm", year="2025")  # JHamm25
user2 = create_username(year="2023", forename="Quintin", surname="Bacon")  # QBacon23

Default parameters

Keyword arguments are useful and improve readability when using default parameters.

def create_username(forename, surname, year="2025"):
    username = f"{forename[0]}{surname}{year[2:]}"
    return username
 
user = create_username("Frances", "Ford", year="2021")  # FFord21