蟒蛇;类实例 [英] Python; class instances

问题描述

假设我有一个类，调用 class1，有3个类变量 var1，var2，var3， __ init __ 方法将传递的参数分配给类变量：

Suppose I have a class, call it class1, with 3 class variables var1,var2,var3, and __init__ method, which assigns passed arguments to the class variables:

class class1(object):
    var1 = 0
    var2 = 0
    var3 = 0

    def __init__(self,a,b,c):
       class1.var1 = a
       class1.var2 = b
       class1.var3 = c

现在我要创建同一个类的两个实例：

Now I'm going to make two instances of the same class:

obj1 = class1(1,2,3)
obj2 = class1(4,5,6)

现在，让我们来看看变量值：

And now, let's take a look at variables values:

print (obj1.var1, obj1.var2,obj1.var3)
4 5 6
print (obj2.var1, obj2.var2,obj2.var3)
4 5 6

不应 obj1 有值1,2,3吗？为什么第二个实例的 __ init __ 方法更改第一个实例中的值（ obj1 ）？

Shouldn't obj1 have values 1,2,3 ? Why __init__ method of the second instance changes vaues in the first instance(obj1)? And how to make two independent separate instances of a class?

推荐答案

在类定义中声明的变量，但不在内部方法，将是类变量。

Variables declared in the class definition, but not inside a method, will be class variables. In other words, they will be the same for the whole class.

要解决这个问题，你可以在 __ init __ 方法，因此它们变成实例变量：

To solve this you could declare them in the __init__ method, so they become instance variables:

class class1():
    def __init__(self,a,b,c):
        self.var1 = a
        self.var2 = b
        self.var3 = c

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