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Questions tagged [structural-pattern-matching]

This tag is for questions about Python's Structural Pattern Matching feature, introduced in version 3.10

PEP 634 introduced the specification of the Structural Pattern Matching feature starting with . In addition, PEP 635 introduces the motivations and rationale behind this new feature. Lastly, PEP 636 introduces a hands-on tutorial of the different ways to use this feature.

The feature offers a convenient, dynamic way to parse different inputs against desired patterns, and to specify the ways to handle these patterns accordingly. This is done using the new soft keywords ( i.e. they are not reserved words in other grammatical contexts) match and case.

For example:

match string:
    case "value1":
        # do something if the input is "value1"
    case _:
        # do something for any other case

will match the input string against the different cases (patterns), when _ is used as a wildcard - the default case which always matches.

Some of the other useful constructs are:

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How to use 'in' a python match case statement

I'd like to check if a value is in a list in the 'case' of a structural pattern matching. Put it another way, I'd like to translate the following "if else" in a match case statement. list1 = [4, 2, 7] var = 2 if var == 1: print("case1") elif…
u2gilles
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Match/Case used to decide what keys JSON response contains

I am trying to apply a match/case in my script where I want to do some action based on the JSON response from the API call: response_types = 1. -> {'data': [{'id': 1485037059173588994}]} 2. -> {'data': [{'media': 1423364523411623943}]} 3. ->…
Ralphie Needham
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How to call a function inside python's match pattern?

I have code join_prefix = lambda text: config.get("CM_PREFIX") + text match shlex.split(message.message): case [join_prefix("setmode"), mode] if mode.isdigit(): await self._set_mode_handler(message, int(mode)) return case…
h3xcode
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Python Structural pattern matching - pass Object to case statement

this is my code class BasePlayer: @staticmethod def walk(direction): print(f"I run into {direction}") class Archer(BasePlayer): @staticmethod def shoot(): print("shoot") class Wizard(BasePlayer): @staticmethod …
Data Mastery
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Confusion between use of `|` to combine two dictionaries vs in match-case

we know that | is used to combine two dictionaries, like, dct_1 = {'a': 1} dct_2 = {'b': 2} print(dct_1 | dct_2) gives, {'a': 1, 'b': 2} but if one wants to use the same | in match-case to combine two dictionaries, x = {'a': 1, 'b': 2} d = {'a':…
apostofes
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Matching an element in an unknown sequence location using structural pattern matching in Python 3.10

Is there any clever way to match on an element in an unknown location in a sequence of unknown length using structural pattern matching in Python 3.10? Below is a non-working example illustrating what I'd like to do. match [1, 2, "3", 4, 5]: …
Daniel Hjertholm
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How to implement @dataclass to define arithmetic operations in Python?

I'm learning Python on my own and I found a task that requires using a decorator @dataclass to create a class with basic arithmetic operations. from dataclasses import dataclass from numbers import Number @dataclass class MyClass: x: float …
Heike Heinrich
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