exceptions

class AttrsAttributeNotFoundError(ValueError):
    """
    An ``attrs`` function couldn't find an attribute that the user asked for.

    .. versionadded:: 16.2.0
    """

class DefaultAlreadySetError(RuntimeError):
    """
    A default has been set using ``attr.ib()`` and is attempted to be reset
    using the decorator.

    .. versionadded:: 17.1.0
    """

class FrozenAttributeError(FrozenError):
    """
    A frozen attribute has been attempted to be modified.

    .. versionadded:: 20.1.0
    """

class FrozenError(AttributeError):
    """
    A frozen/immutable instance or attribute have been attempted to be
    modified.

    It mirrors the behavior of ``namedtuples`` by using the same error message
    and subclassing `AttributeError`.

    .. versionadded:: 20.1.0
    """

    msg = "can't set attribute"
    args = [msg]

class FrozenInstanceError(FrozenError):
    """
    A frozen instance has been attempted to be modified.

    .. versionadded:: 16.1.0
    """

class NotAnAttrsClassError(ValueError):
    """
    A non-``attrs`` class has been passed into an ``attrs`` function.

    .. versionadded:: 16.2.0
    """

class NotCallableError(TypeError):
    """
    A ``attr.ib()`` requiring a callable has been set with a value
    that is not callable.

    .. versionadded:: 19.2.0
    """

    def __init__(self, msg, value):
        super(TypeError, self).__init__(msg, value)
        self.msg = msg
        self.value = value

    def __str__(self):
        return str(self.msg)

class PythonTooOldError(RuntimeError):
    """
    It was attempted to use an ``attrs`` feature that requires a newer Python
    version.

    .. versionadded:: 18.2.0
    """

class UnannotatedAttributeError(RuntimeError):
    """
    A class with ``auto_attribs=True`` has an ``attr.ib()`` without a type
    annotation.

    .. versionadded:: 17.3.0
    """