Python - match case

 

Introduced in Python 3.10, the match statement (often called Structural Pattern Matching) is a powerful upgrade to the traditional if/elif/else chain. It works similarly to "switch" statements in other languages but is much more capable.

The Basic Syntax

At its simplest, match takes a variable and compares it against different patterns.

command = "quit"

match command:
    case "start":
        print("System starting...")
    case "stop":
        print("System stopping...")
    case "quit":
        print("Exiting...")
    case _:
        print("Unknown command")

• match: The variable you want to inspect.

• case: The specific pattern you are looking for.

• _ (The Underscore): A wildcard that acts as a "catch-all" (like else). It matches anything if no previous case did.

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Advanced Features

1. Combining Multiple Patterns

You can use the pipe operator (|) to match multiple values in a single case.

status = 404

match status:
    case 200 | 201:
        print("Success")
    case 400 | 404 | 405:
        print("Client Error")
    case _:
        print("Other status")

2. Matching with Guards (if statements)

You can add an if condition to a case to create a "guard." The case only matches if the pattern fits and the condition is true.

point = (3, 5)

match point:
    case (x, y) if x == y:
        print(f"The point is on the diagonal at {x}")
    case (x, y):
        print(f"Point is at {x}, {y}")

3. Capturing Values

One of the best features of match is the ability to "unpack" data structures like lists or dictionaries.

user_input = ["move", "north"]

match user_input:
    case ["quit"]:
        exit()
    case ["move", direction]:
        print(f"Moving the character {direction}")
    case ["jump", height]:
        print(f"Jumping {height} meters high")

In the example above, if the list is ["move", "north"], Python automatically assigns "north" to the variable direction.

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When to use match vs if/elif

Feature	if/elif/else	match/case
Simple Comparisons	Excellent	Good
Complex Logic	Best	Can get messy
Unpacking Data	Manual and wordy	Automatic and clean
Readability	Good for few conditions	Best for many patterns

Quick Tips

• Order Matters: Python checks cases from top to bottom. Always put specific patterns first and the wildcard _ last.

• Version Check: Remember that this only works in Python 3.10 or newer.