Match

Suppose we have a variable, either a simple one like an Int or a more complex tuple or list, and want to test its contents. A Python match-statement can help with this requirement.

While an if-statement could work instead of match, the match-statement is more elegant and can make programs more maintainable. Match usually results in shorter code.

Example

This program has several possible match-statements, each with various case-statements. It is meant to demonstrate many possible ways of using match.

# Part 1: use simple match statement with default case.
value = 10
match value:
    case 5:
        print("Five matched!")
    case 7:
        print("Seven matched!")
    case _:
        print("Default case")

# Part 2: use if statement inside case statement.
done = True
match value:
    case 10 if done:
        print("Done, case 10 matched")
    case _:
        print("Not reached")

# Part 3: capture a variable as part of a case statement inside a match.
animal = ("bird", 10)
match animal:
    case ("cat", weight):
        print("Cat weight is", weight)
    case ("bird", weight):
        print("Bird weight is", weight)

# Part 4: use multiple cases in a single statement.
code = 10
match code:
    case 5 | 10 | 15:
        print("Multiple of 5")
    case _:
        print("Not reached")

# Part 5: match a list.
items = ["bird", "frog", "dog"]
match items:
    case []:
        print("Empty")
    case ["bird", "frog", x]:
        print("Matched bird, frog and", x)
Default case
Done, case 10 matched
Bird weight is 10
Multiple of 5
Matched bird, frog and dog

It is possible to replace if-statements with equivalent match-statements in Python, and this can sometimes simplify the syntax of programs.