Functions Advanced

Arbitrary Arguments

Via arbitrary arguments a function can receive a dynamic count of arguments.

They're specified by adding a * prefix.

Let's look at the following example:

def printData(*numbers): argCount = len(numbers) print("Arguments count: ", argCount) print("0 ->", numbers[0]) print("1 ->", numbers[1]) printData(1,4,7) printData(2,9,3,8)

Output:

Arguments count: 3 0 -> 1 1 -> 4 Arguments count: 4 0 -> 2 1 -> 9

Multiple arguments are passed to printData but all of them are accessed only by the single *numbers argument.

At line 2 the len function is used to get the count of the passed arguments.

At lines 4 and 5 the passed arguments are accessed via indexes starting from 0.

Keyword Arguments

For such arguments the order doesn't matter and they can be set via "key = value" syntax.

Let's look at the following example:

def printPersonData(name, surname, age): print("Name:", name) print("Surname:", surname) print("Age:", age) printPersonData(age = 20, surname = "Emil", name = "Bill")

Output:

Name: Bill Surname: Emil Age: 20

The order of the passed arguments is not the same as the arguments order of the function definition.

age = 20 sets value of 20 to the age argument.

Arbitrary Keyword Arguments

Suitable if the count of keyword arguments is unknown.

They're specified by adding a ** prefix.

Example:

def printCarsData(**data): print("Make:", data["make"]) print("Model:", data["model"]) print("Hp:", data["hp"]) printCarsData(hp = 90, make = "Toyota", model = "Corolla")

Output:

Make: Toyota Model: Corolla Hp: 90

The values for the passed arguments is stored inside data.

data["make"] accesses the passed value for make which is "Toyota".