"match" Statement for Pattern Match

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∟"match" Statement for Pattern Match

This section provides a quick introduction of 'match' statement, which selects a block of sub-statements to execute based on pattern match algorithms.

What Is "match" Statement? A "match" statement is a compound statement that selects a block of sub-statements to execute based on pattern match algorithms. "match" statements were introduced in 2021 in Python 3.10.

Here is the syntax of "match" statements:

match SUBJECT:
    case PATTHEN_1 [if CONDITION_1]:
        SUITE_1
    case PATTHEN_2 [if CONDITION_2]:
        SUITE_2
    ...
    case _:
        SUITE_n

Logically, a "match" statement written in the above syntax is equivalent to the following code using "if" statements:

if SUITE_1_matches_SUBJECT [and CONDITION_1]:
    SUITE_1
elif SUITE_2_matches_SUBJECT [and CONDITION_2]:
    SUITE_2
...
else
    SUITE_n

I don't have Python 3.10 installed yet. So I am not able to run any test on "match" statements. But you can look at the following example given in the Python 3.10 manual.

>>> flag = False
>>> match (100, 200):
...    case (100, 300):  # Mismatch: 200 != 300
...        print('Case 1')
...    case (100, 200) if flag:  # Successful match, but guard fails
...        print('Case 2')
...    case (100, y):  # Matches and binds y to 200
...        print(f'Case 3, y: {y}')
...    case _:  # Pattern not attempted
...        print('Case 4, I match anything!')
...
Case 3, y: 200