Class methodcaller

dask/utils.py:1209–1243

Return a callable object that calls the given method on its operand. Unlike the builtin `operator.methodcaller`, instances of this class are cached and arguments are passed at call time instead of build time.

class methodcaller:
    """
    Return a callable object that calls the given method on its operand.

    Unlike the builtin `operator.methodcaller`, instances of this class are
    cached and arguments are passed at call time instead of build time.
    """

    __slots__ = ("method",)
    method: str

    @property
    def func(self) -> str:
        # For `funcname` to work
        return self.method

    def __new__(cls, method: str):
        try:
            return _method_cache[method]
        except KeyError:
            self = object.__new__(cls)
            self.method = method
            _method_cache[method] = self
            return self

    def __call__(self, __obj, *args, **kwargs):
        return getattr(__obj, self.method)(*args, **kwargs)

    def __reduce__(self):
        return (methodcaller, (self.method,))

    def __str__(self):
        return f"<{self.__class__.__name__}: {self.method}>"

    __repr__ = __str__


class itemgetter: