一个类的定制双星运算符？ [英] Custom double star operator for a class?

问题描述

如何实现自定义双星运算符（ ** ）进行解包，类似于 __ iter __ 单星运算符（ * ）？

How does one implement custom double star operator (**) for unpacking, similar to how __iter__ works with single star operator (*)?

例如：

class PlayerManager(object):

    def __init__(self, players=None):
        self.players = players or []

    # Made up method to support ** operator
    def __dict_iter__(self):
        for player in self.players:
            yield get_steamid(player), player

def print_players(**players):
    print(players)

player_manager = PlayerManager([list, of, players])
print_players(player_manager)

输出：

{
    'STEAM_0:0:02201': <Player object at 0x0000000000>,
    'STEAM_0:0:10232': <Player object at 0x0000000064>,
    'STEAM_0:0:73602': <Player object at 0x0000000128>
}

推荐答案

映射。这里有一个例子：

As @ShadowRanger says, implement Mapping. Here's an example:

from collections.abc import Mapping

class Foo(Mapping):
    def __iter__(self):
        yield "a"
        yield "b"

    def __len__(self):
        return 2

    def __getitem__(self, item):
        return ord(item)

f = Foo()

print(*f)
print(dict(**f))

程序输出：

a b
{'a': 97, 'b': 98}

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