How to access the matched value in the default case of structural pattern matching?

user_432509 0
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With Python 3.10's match statement, is it possible to use the value met in the default case?

Or does this need to be assigned a variable before match so it can be used in the default case?

match expensive_calculation(argument):
    case 'APPLE':
        value = 'FOO'
    case 'ORANGE':
        value = 'BAR'
    case _:
        raise Exception(
           "Wrong kind of fruit found: " +
           str(expensive_calculation(argument))
           # ^ is it possible to get the default value in this case?
        )
python-3.10 pattern-matching python
1 Answers

You can use an as pattern:

match expensive_calculation(argument):
  case 'APPLE':
    value = 'FOO'
  case 'ORANGE':
    value = 'BAR'
  case _ as argument: #here, using `as` to save the wildcard default to `argument`
    raise Exception(f"Wrong kind of fruit found: {str(argument)}")
user_73267380
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