Course Content

Python Functions Tutorial

1. What is Function in Python?

What Is Function?Challenge: Building functions Arguments Return Value Function Body Built-in Functions

2. Positional and Optional Arguments

Positional Arguments Challenge: Positional Arguments Optional Arguments Challenge: Optional Arguments

3. Arbitrary Arguments

Arbitrary Arguments Arbitrary Keyword Arguments Combination of Positional and Optional Arguments

4. Function Return Value Specification

Single Return Value Multiple Return Values None Return Value Generator Functions Challenge: Traffic lights

5. Recursion and Lambda Functions

Recursion Challenge: Pyramid Lambda Functions Immediately Invoked Lambda Expression Writing Effective and Maintainable Functions

Optional Arguments

What will happen if one of the positional arguments is not specified? Let's look at the example:


              123456
            
# Function with two positional arguments
def greet(name, age):
    print(f'Hello, {name}! You are {age} years old.')

# Calling the `greet()` function with one missing argument
greet(name='Alex')

An error occurred when we forgot to specify some of the positional arguments. In real projects, this behavior is unacceptable, as it generates many bugs and significantly impacts the system's fault tolerance. One approach to mitigate this issue is by employing default arguments.

These arguments are optional when calling the function, as the default value will be used if no value is specified for that argument.

To define an optional argument, you can assign a default value to the corresponding parameter in the function definition. Here's an example:


              12345
            
def greet(name, age=0):
    print(f'Hello, {name}! You are {age} years old.')

# Calling the `greet()` function with missing optional argument
greet(name='Alex')

But there is one important rule when using optional arguments - they must be specified after all non-optional arguments. If this rule is not met, the error will occur.


              12345
            
def greet(name='Alex', age):
    print(f'Hello, {name}! You are {age} years old.')

# Calling the `greet()` function with optional argument before non-optional 
greet(age=35)

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 3