Lesson 12: Match Statements (Switch)

Introduction to Match Statements

Match statements (introduced in Python 3.10) are similar to switch statements in other languages. They provide a clean way to compare a value against multiple patterns and execute code based on which pattern matches.

Match statements are more powerful than traditional if-elif chains because they support pattern matching, making code more readable and less error-prone.

Basic Match Statement

The basic syntax matches a value against specific cases. The underscore _ acts as a default case (like else):

match.py
day = "Monday"

match day:
    case "Monday":
        print("Start of week")
    case "Friday":
        print("TGIF!")
    case _:
        print("Regular day")

Multiple Cases

You can combine multiple cases using the pipe operator | (OR), allowing a single block to handle multiple values:

multiple_cases.py
day = "Saturday"

match day:
    case "Monday" | "Tuesday" | "Wednesday" | "Thursday":
        print("Weekday")
    case "Friday":
        print("TGIF!")
    case "Saturday" | "Sunday":
        print("Weekend!")
    case _:
        print("Invalid day")

Pattern Matching with Guards

You can add conditions (guards) to cases using if to create more complex matching logic:

guards.py
age = 25
status = "active"

match status:
    case "active" if age >= 18:
        print("Adult account")
    case "active":
        print("Minor account")
    case "inactive":
        print("Account suspended")
    case _:
        print("Unknown status")

Matching Different Types

Match statements can handle different data types and patterns. Here's an example with numbers:

types.py
value = 42

match value:
    case 0:
        print("Zero")
    case 1 | 2 | 3:
        print("Small number")
    case 42:
        print("The answer to everything!")
    case _ if value > 100:
        print("Large number")
    case _:
        print("Other number")

Match vs If-Elif

Match statements are often more readable than long if-elif chains, especially when comparing a single variable against multiple values:

💡 When to Use Match

Use match when comparing one value against multiple possibilities. It's cleaner and more Pythonic for this use case.

💡 When to Use If-Elif

Use if-elif when conditions are complex or involve multiple variables, or when you need to check different types of conditions.

Practical Example: Command Handler

Here's a practical example using match to handle different commands:

command_handler.py
command = "start"

match command.lower():
    case "start":
        print("Starting application...")
    case "stop":
        print("Stopping application...")
    case "pause":
        print("Pausing application...")
    case "resume":
        print("Resuming application...")
    case _:
        print(f"Unknown command: {command}")

Match Statements (Switch)