Python更改类变量 [英] Python changing class variables

问题描述

好吧，这次我会尝试并非常清楚。

Okay, I'll try and be extremely clear this time.

class Yes:

    def __init__(self):
        self.a=1

    def yes(self):
        if self.a==1:
            print "Yes"
        else:
            print "No, but yes"

class No(Yes):

    def no(self):
        if self.a==1:
            print "No"
        else:
            print "Yes, but no"
        self.a-=1 #Note this line

现在，在运行时：

Yes().yes()
No().no()
Yes().yes()
No().no()

我要打印出来：

Yes
No
No, but yes
Yes, but no

它给我：

Yes
No
Yes
No

现在，我知道原因是因为我只更改了Self.a的值无课（备注那条线？）。我想知道是否仍然可以在Yes类中同时在No类中对其进行更改（例如是否可以代替self.a- = 1插入某些东西，这样还是可以的）。

Now, I know the reason why is because I'm only changing the value of Self.a in the No class(Remember that line?). I want to know if there is anyway to change it in the Yes class while still in the No class (like if there was something that I could plug in in place of the self.a-=1 that would work).

推荐答案

我不确定您有什么可能的用途，但是...

I'm not sure what possible use you have for this, but...

您要操作 class 变量，但是您要继续寻址实例变量。如果需要类变量，请使用类变量！

You want to manipulate a class variable, but you keep addressing instance variables. If you want a class variable, use a class variable!

class Yes:
    a = 1 # initialize class var.
    def __init__(self):
        self.a = 1 # point of this is what?

    def yes(self):
        if Yes.a==1: # check class var
            print "Yes"
        else:
            print "No, but yes"

class No(Yes):

    def no(self):
        if Yes.a==1: # check class var
            print "No"
        else:
            print "Yes, but no"
        Yes.a-=1 # alter class var

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