The match case statement, introduced in Python 3.10 as a structural pattern matching tool, is designed to simplify and enhance readability when dealing with complex conditional logic. It offers a more readable and concise alternative to multiple if...elif...else statements, especially when testing a variable against multiple conditions.

The match statement is similar to the switch case statements found in other languages but is more powerful due to its capabilities for pattern matching.

Syntax of the Match Statement

The match statement allows you to compare a value against several possible matches. Each case can execute a block of code designed for that specific match.

• expression: This is the value that you’re comparing against the patterns in each case.
• pattern: These are specific conditions or values that the expression might match. Python checks the patterns in the order they are written.
• _: This is a wildcard pattern that acts as the default case, catching all values that don’t match any previous pattern.

Execution Flow

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Example

Explanation:

• status_code = 404: Assigns the value 404 to the variable status_code.
• match status_code: Starts a match statement that will check the value of status_code.
• case 200: Checks if status_code equals 200. It does not, so it skips to the next case.
• case 404: Checks if status_code equals 404. It does, so it executes the print statement.
• The remaining cases and the default case (case _) are not executed because a match has already been found.

Combined Cases in Match Statement

In the match statement, you can handle multiple possible values for a single case using the | operator, which functions like an “or” in this context. This is useful when different values should trigger the same response, making your code cleaner and more straightforward.

Example

Explanation:

• day = "Tuesday": Assigns the string "Tuesday" to the variable day.
• match day:: Begins a match statement that evaluates the variable day.
• case "Monday" | "Friday":: Checks if day is either "Monday" or "Friday". If so, executes the associated block.
• case "Wednesday" | "Tuesday":: Checks if day is either "Wednesday" or "Tuesday". If so, executes the associated block.
• case _: : The wildcard case _ catches all other values that haven’t matched any previous cases.

List as the Argument in Match Case Statement

The match statement can also work with lists as arguments, allowing you to match against the contents of a list. This is particularly useful for scenarios where you want to check the structure or presence of certain elements in a list.

Example

Explanation:

• colors = ["red", "blue", "green"]: Assigns a list of three colors to the variable colors.
• match colors:: Starts the match statement that checks the colors list.
• case ["red", *others]:: Matches if the first element in the list is "red". The *others is a wildcard that captures the rest of the list, regardless of its contents.
• case ["blue", *others]:: Matches if the first element is "blue", with *others again capturing the rest of the list.
• case _: : Catches any list that doesn’t start with "red" or "blue".

Using “if” in “Case” Clause

You can incorporate conditions within a case clause using the if keyword to add more specific logic to your matches. This allows for detailed and conditional pattern matching within the match statement.

Example

Explanation:

• person = (25, "Engineer"): Assigns a tuple containing an integer and a string to person.
• match person:: Initiates a match statement to evaluate person.
• case (age, profession) if age > 20 and profession == "Engineer":: Matches if person is a tuple where the first element (age) is greater than 20 and the second element (profession) is "Engineer".
• case _: : Catches all other values and patterns not matched by the first case.

These explanations and examples provide a thorough look into using the match case statement effectively, illustrating its power and flexibility in handling complex conditional logic in Python.