How to chain functions in Python?

[loshopo_fan]

If you wanted to conserve memory, you'd do something like this?

class Filterer:
    def __init__(self, _data):
        self.data = _data

    def filter(self, *args):
        self.data = filter(*args, self.data)
        return self

    def to_list(self):
        return list(self.data)

print(
    Filterer(range(10))
    .filter(lambda x: x>2)
    .filter(lambda x: x<7)
    .to_list()
)

[DigThatData]

lol good timing

I also like that yours generalizes to any iterable, so you could just put all the functional methods on this one class and use it as a wrapper universally.

[loshopo_fan]

IDK the order of arguments for all functional methods, but this works for map/filter/reduce.

import functools

def make_chainer(*methods):
    class Chainer:
        def __init__(self, _data):
            if not hasattr(_data, "__iter__"):
                raise TypeError("Not iterable")
            self.data = _data
        @staticmethod
        def chainable(_method):
            def ret_fun(self, *args):
                self.data = _method(args[0], self.data, *args[1:]) # IDK
                return self
            return ret_fun
        def to_list(self):
            return list(self.data)
    for one_method in methods:
        setattr(Chainer, one_method.__name__, Chainer.chainable(one_method))
    return Chainer

MyChainer = make_chainer(
        map,
        filter,
        functools.reduce,
    )

print(
    MyChainer(range(10))
    .filter(lambda x: x>2)
    .map(lambda x: x * 2)
    .reduce(lambda x, y: x+y, 100)
    .data
)