Function decide_callable_or_boolean

src/attr/_make.py:1265–1273

Decide whether a key function is used.

(value)

        raise ValueError(msg)

    def decide_callable_or_boolean(value):
        """
        Decide whether a key function is used.
        """
        if callable(value):
            value, key = True, value
        else:
            key = None
        return value, key

    # cmp takes precedence due to bw-compatibility.
    if cmp is not None: