Python Match Syntax

Introduced in Python 3.10 (PEP 634), the match statement provides structural pattern matching.

Basic Syntax

python

match command:
    case "quit":
        quit()
    case "reset":
        reset()
    case _:
        print("Unknown command")

Key Features

1. Structural Matching

Matches against the structure of data (sequences, mappings, objects).

python

match point:
    case (0, 0):
        print("Origin")
    case (0, y):
        print(f"Y={y}")
    case (x, 0):
        print(f"X={x}")
    case (x, y):
        print(f"X={x}, Y={y}")

2. Class Matching

Matches against class attributes.

python

@dataclass
class Point:
    x: int
    y: int

match point:
    case Point(x=0, y=0):
        print("Origin")
    case Point(x=0, y=y):
        print(f"Y={y}")

3. Guards

if clauses can be added to cases.

python

match point:
    case Point(x, y) if x == y:
        print(f"Y=X at {x}")
    case Point(x, y):
        print(f"Not on diagonal")

4. Capture Patterns

Variables can capture parts of the match.

python

match command.split():
    case ["go", direction]:
        print(f"Going {direction}")
    case ["drop", *items]:
        print(f"Dropping {items}")

5. OR Patterns

Combine patterns with |.

python

match status:
    case 401 | 403 | 404:
        print("Not allowed")
    case 200:
        print("OK")

Note

Python's match is a statement, not an expression. It does not return a value.