在 Python 中更改另一个类中的属性

Question

我一直在尝试从类 Pod 更改类 Inventory 中的列表，但是我收到一个错误，提示我从一个空集合中弹出。无论如何，我可以从我知道已填充的 Inventory 实例的列表中弹出吗？本质上，我正在尝试将小部件从 Inventory 转移到 Pod。

class Widget():

    def __init__(self):
        self.cost = 6
        self.value = 9


class Inventory():

    def __init__(self):
        self.widgets_inv = []
        self.cost_inv = 0
        self.value_inv = 0

    def buy_inv(self):
        x = int(input("How many widgets to you want to add to inventory? "))
        for i in range(0, x):
            self.widgets_inv.append(Widget())

    def get_inv(self):
        print("You have " + str(len(self.widgets_inv)) + " widgets in inventory.")

    def cost_of_inv(self):
        cost_inv = len(self.widgets_inv) * Widget().cost
        print("The current cost of your inventory is: " + cost_inv + " USD.")

    def value_of_inv(self):
        val_inv = len(self.widgets_inv) * Widget().value
        print("The current value of your inventory is: " + val_inv + " USD.")

class Pod():
    """A pod is a grouping of several widgets.  Widgets are sold in pods"""

    def __init__(self):
        self.pod = []

    def creat_pod(self):
        x = int(input("How many widgets would you like to place in this pod? "))
        for i in range(0, x):
            self.pod.append(Widget())
            Inventory().widgets_inv.pop()

Answer 1

您应该修改creat_pod方法，以便您可以移交 Inventory 对象。这允许您在调用creat_pod -method之前将小部件添加到库存对象：

def creat_pod(self, inventory):
        x = int(input("How many widgets would you like to place in this pod? "))
        for i in range(0, x):
            self.pod.append(Widget())
            inventory.widgets_inv.pop()

在您的原始代码中，您始终创建一个新的库存对象，因此它具有空的小部件列表：

Inventory().widgets_inv.pop()