在Python中访问父类的静态类变量 [英] Access static class variable of parent class in Python

问题描述

我喜欢这样

class A:
  __a = 0
  def __init__(self):
    A.__a = A.__a + 1
  def a(self):
    return A.__a

class B(A):
  def __init__(self):
    # how can I access / modify A.__a here?
    A.__a = A.__a + 1 # does not work
  def a(self):
    return A.__a

我可以在 B 中访问 __ a 类变量吗？可以写 a 而不是 __ a ，这是唯一的方法吗？ （我猜答案可能很短：是的）。

Can I access the __a class variable in B? It's possible writing a instead of __a, is this the only way? (I guess the answer might be rather short: yes :)

推荐答案

所以， __ a 不是 static 变量，它是一个类变量。并且由于双重前导下划线，它是名称损坏变量。也就是说，为了使其成为伪私有，它已被自动重命名为 _< classname> __< variablename> 而不是 __< variablename> 。它仍然可以被的实例访问只作为 __< variablename> ，子类不会得到这种特殊处理。

So, __a isn't a static variable, it's a class variable. And because of the double leading underscore, it's a name mangled variable. That is, to make it pseudo-private, it's been automagically renamed to _<classname>__<variablename> instead of __<variablename>. It can still be accessed by instances of that class only as __<variablename>, subclasses don't get this special treatment.

我建议您不要使用双前导下划线，只使用一个下划线来（a）标记它是私有的，以及（b）避免名称重整。

I would recommend that you not use the double leading underscore, just a single underscore to (a) mark that it is private, and (b) to avoid the name mangling.

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