Python object 字典属性被附加到每个循环迭代而不是被垃圾收集

Question

I have created an Game class which has a dictionary attribute of players as an attribute, which should have ~36 players in it.

I am iterating though a loop, creating a new instance of a Game object with each iteration and printing the contents of each player onto a csv file.

However, with each iteration although a new object is created, it seems that the player attribute is being appended to rather than being garbage collected.

sheet = open('playerGames.csv', 'w+')
gameNum = 2018020001

while gameNum < 2018020015:

    game = Game(gameNum)

    print(len(game.players), end=", ")

    for player in game.players:
        for stat in game.players[player]:
            sheet.write(str(game.players[player][stat]) + ",")
        sheet.write("\n")
    game = None

    gameNum = gameNum + 1

The print statement in the above should print a number about 36 each time however it outputs the following 36, 72, 108, 144, 163, 199, 217, 253, 289, 325, 361, 397, 433, 469

Should the garbage collection not clear this up? I have added the game = None statement in hopes that the entire object gets collected, however that does not seem to work.

Answer 1

Given that players is defined as a global variable, you need to reset in your constructor, something like this:

class Game:

    def __init__(self, n):
        players = dict()

Having a global variable is a bad practice in any language, see this . If players is a property of the Game objects you should do instead:

class Game:

    def __init__(self, n):
        self.players = { }  # dictionary construction expression