Question

我正在编写一个程序，您可以将其放入主队，客队以及游戏结果中。我希望团队的数据能够根据这一点进行更改，而且大部分都是如此。但是我无法让“点数”，“净胜球”和“玩”（游戏）改变！这是我到目前为止写的代码：

class team:
    def __init__(self, name, wins, drawn, losses, goals_for, goals_against):
        self.name = name
        self.wins = int(wins)
        self.drawn = int(drawn)
        self.losses = int(losses)
        self.goals_for = int(goals_for)
        self.goals_against = int(goals_against)
        self.goals_difference = (self.goals_for - self.goals_against)
        self.points = ((self.wins * 3) + self.drawn)
        self.played = (self.wins + self.drawn + self.losses)
    def __repr__(self):
        return 'Name:{} P:{} W:{} D:{} L:{} GF:{} GA:{} GD:{} PTS:{}'.format(self.name, self.played, self.wins, self.drawn, self.losses, self.goals_for, self.goals_against, self.goals_difference, self.points)    

detroit_red_wings = team("Detroit", 1, 0, 3, 4, 5)
los_angeles_kings = team("LA", 0, 1, 4, 3, 7)
toronto_maple_leafs = team("Toronto", 1, 2, 2, 3, 6)

teamlist = [detroit_red_wings, los_angeles_kings, toronto_maple_leafs]
print(teamlist)

class data_input:
    def home_team_input(self):
        home_team = input("Type in the home team: ")
        for i in teamlist:
            if i.name == home_team:
                return i
    def away_team_input(self):           
        away_team = input("Type in the away team: ")
        for t in teamlist:
            if t.name == away_team:
                return t
    def result_input(self):
        goals_home_team = int(input("Type in the number of goals made by the home team: "))
        goals_away_team = int(input("Type in the number of goals made by the away team: "))
        return (goals_home_team, goals_away_team)

def adding_result():
    home_team = data_input.home_team_input()
    away_team = data_input.away_team_input()
    goals_home_team, goals_away_team = data_input.result_input()

    home_team.goals_for += goals_home_team
    home_team.goals_against += goals_away_team
    away_team.goals_for += goals_away_team
    away_team.goals_against += goals_home_team

    if goals_home_team > goals_away_team:
        home_team.wins += 1
        away_team.losses += 1
    if goals_home_team < goals_away_team:
        away_team.wins += 1
        home_team.losses += 1
    if goals_home_team == goals_away_team:
        home_team.drawn += 1
        away_team.drawn += 1

data_input = data_input()
adding_result()
print(teamlist)

我在课程__init__的{{1}}方法中编写了属性说明，您可以看到这些点取决于team。这一切都在我创建对象时有效，但当我输入新游戏的结果时，wins不会改变（points或played也不会）。这让我感到惊讶，因为当我在goals_difference函数中输入游戏结果时，其他属性会发生变化。

Answer 1

如果更新team类以生成计算字段属性，则属性函数将始终返回正确的结果。如果您尝试设置这些属性，也会出现错误，因为它们不可设置，即它们是对其他设置数据进行计算的结果。

class team:
    def __init__(self, name, wins, drawn, losses, goals_for, goals_against):
        self.name = name
        self.wins = int(wins)
        self.drawn = int(drawn)
        self.losses = int(losses)
        self.goals_for = int(goals_for)
        self.goals_against = int(goals_against)

    @property
    def goals_difference(self):
        return self.goals_for - self.goals_against

    @property
    def points(self):
        return self.wins * 3 + self.drawn

    @property
    def played(self):
        return self.wins + self.drawn + self.losses

    def __repr__(self):
        return 'Name:{} P:{} W:{} D:{} L:{} GF:{} GA:{} GD:{} PTS:{}'.format(
            self.name, self.played, self.wins, self.drawn, self.losses,
            self.goals_for, self.goals_against, self.goals_difference,
            self.points)

我还会考虑制作W / L / D和GF / GA初始化程序的tupples或词典，而不是将5个变量传递给初始化程序。

Answer 2

points，goals_difference和played不会更新，因为更新其他属性后，__init__方法不会再次运行 - 您只是使用新值明确更新其他属性。请注意，这些不更新的属性由值分配，而不是通过引用分配，除非您明确这样做，否则您的对象无法知道应更新这些属性。

您可以做几件事 - 一个简单的选项可能是提供一种更新聚合属性的方法，您可以在显式更改其他属性后调用。我会将所有属性简单地作为其他属性的数学公式（所以points，goals_difference和played），并从初始化方法中删除它们。如果你真的需要这些看起来像这个

的属性，请调用像update_aggregates这样的小方法

def update_aggregates(self):
    self.goals_difference = (self.goals_for - self.goals_against)
    self.points = ((self.wins * 3) + self.drawn)
    self.played = (self.wins + self.drawn + self.losses)

编辑：忽略我的简单尝试，Steve Cohen提出的解决方案无论如何都更好 - 使用@property可确保您的值始终适当更新，而无需手动调用

制作使用其他属性

2 个答案: