Python类变量名vs __name__ [英] Python class variable name vs __name__

问题描述

我试图理解一个Python类对象赋值的变量和该类对象的 __ name __ 属性之间的关系。例如：

I'm trying to understand the relationship between the variable a Python class object is assigned to and the __name__ attribute for that class object. For example:

In [1]: class Foo(object):
   ...:     pass
   ...: 

In [2]: Foo.__name__ = 'Bar'

In [3]: Foo.__name__
Out[3]: 'Bar'

In [4]: Foo
Out[4]: __main__.Bar

In [5]: Bar
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-5-962d3beb4fd6> in <module>()
----> 1 Bar

NameError: name 'Bar' is not defined

似乎我已经改变了 __ name __ 属性的类，但我不能通过该名称引用它。我知道这有点一般，但可以有人解释 Foo 和 Foo .__ name __ ？之间的关系？

So it seems like I have changed the __name__ attribute of the class but I can't refer to it by that name. I know this is a bit general but could someone explain the relationship between Foo and Foo.__name__?

推荐答案

很简单。

创建一个类时，将使用您所使用的名称创建一个局部变量，指向类，以便您可以使用它。

When you create a class a local variable is created with name you used, pointing at the class so you can use it.

该类还会获得一个属性 __ name __ ，其中包含该变量的名称，因为在某些情况下，

The class also gets an attribute __name__ that contains the name of that variable, because that's handy in certain cases, like pickling.

您可以将局部变量设置为其他值，或者更改 __ name __ 变量，不工作，所以不要这样做。

You can set the local variable to something else, or change the __name__ variable, but then things like pickling won't work, so don't do that.

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