Access attribute of container from member Python

Question

I have a class (PlayerList) that contains Player objects (or subclasses) by inheriting from list builtin. I want each of the Player objects to use the container's attribute true_dice. The problem is that for testing purposes I need each of the players to have the ability to use their own as well, if they are not part of a PlayerList

class PlayerList(list):
    def __init__(plist):
        # plist is a list of Player objects
        self.true_dice = [0,0,0,0]
        super().__init__(plist)

class Player:
    def __init__():
        self.true_dice = "<Magical code that gets containers true_dice>"
    
    def turn(self):
        "..."
        self.true_dice[2] = 1 # Modify true_dice should modify PlayerList's aswell

What is the pythonic way to achieve this? A google search turns up no results.

I was thinking perhaps overriding __getattribute__ would work, but then I would have to store a reference to the PlayerList in the class, and that is a very tightly coupled solution:

class Player:
...
    def __getattribute__(self, attrname):
            if attrname=="true_dice":
                return player_list_reference.true_dice # Defined in __init__
            else:
                return self.__dict__[attrname]

Or perhaps I could run an update function every time a member of the 'PlayerList' changes its true_dice attribute. This would separate concerns rather well...

Please comment any and all requests for edits.

Can you please provide a minimal reproducible example? Is your issue defining the attribute access on Player, using the PlayerList attribute, or falling back to (or preferring?) the Player's own attribute? — MisterMiyagi
– MisterMiyagi, Commented Apr 26, 2022 at 15:29
What is player_list_reference? Is this some global attribute, a placeholder for something to be defined, or a mistyped attribute of Player? — MisterMiyagi
– MisterMiyagi, Commented Apr 26, 2022 at 15:30
If it is for testing purposes, use unittest and mock the attribute or use some other testing framework. — wwii
– wwii, Commented Apr 26, 2022 at 15:37
@MisterMiyagi Like I said "but then I would have to store a reference to the PlayerList in the class, and that is a very tightly coupled solution" It is a reference to the container that it is a part of. — mteam88
– mteam88, Commented Apr 26, 2022 at 15:45

mteam88 · Accepted Answer · 2022-04-26 17:16:36Z

0

All credit to @MisterMiyagi, suggested this answer.

He advocated for something like this if I understand correctly.

class PlayerList(list):
    def __init__(self, plist):
        # plist is a list of Player objects
        self.true_dice = [False, False, False, False]
        for player in plist:
            player.true_dice = self.true_dice # Set true_dice of members
        super().__init__(plist)

class Player:
    def __init__(self, true_dice=None):
        self.true_dice = true_dice
    def turn(self):
        "..."
        self.true_dice[2] = 1 # Modify true_dice should modify PlayerList's aswell

# Implementation Change, not sure how to make this automatic...
pl = PlayerList([Player()])

edited Apr 26, 2022 at 17:16

answered Apr 26, 2022 at 16:11

mteam88

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