1. Python / Говнокод #23145

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    if hasattr(query, "items"):
        query = query.items()
    else:
        # It's a bother at times that strings and string-like objects are
        # sequences.
        try:
            # non-sequence items should not work with len()
            # non-empty strings will fail this
            if len(query) and not isinstance(query[0], tuple):
                raise TypeError
            # Zero-length sequences of all types will get here and succeed,
            # but that's a minor nit.  Since the original implementation
            # allowed empty dicts that type of behavior probably should be
            # preserved for consistency
        except TypeError:
            ty, va, tb = sys.exc_info()
            raise TypeError("not a valid non-string sequence "
                            "or mapping object").with_traceback(tb)

    https://github.com/python/cpython/blob/master/Lib/urllib/parse.py#L848

    Зачем генерировать TypeError, а потом ее ловить и снова кидать?

    Запостил: Admina_mamu_ebal, 23 Июня 2017

    Комментарии (1) RSS

    • ava PashaWNN 10.12.2018 07:42 # 0

      It is not redundant if you want a specific error message. I think that is the point of the code, to indicate the problem to the programmer. So the message is meant to be useful. I can think of three cases:

      >>> urlencode(None) # Non-sequence
      TypeError: not a valid non-string sequence or mapping object
      >>> urlencode({'sized but not indexable'})
      TypeError: not a valid non-string sequence or mapping object
      >>> urlencode('item [0] not a tuple')
      TypeError: not a valid non-string sequence or mapping object

      Официальный ответ с багтрекера.
      Если query не итерируемо или не индексируемо, то TypeError будет брошен ещё в проверке условия, а нужно вывести кастомное сообщение об ошибке, поэтому сделано так.
      Ответить

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