“类本身就是对象"是什么意思? [英] What is meant by "classes themselves are objects"?

问题描述

我只是在阅读有关类的Python文档；它说，在Python中，类本身就是对象".这与C#，Java，Ruby或Smalltalk中的类有何不同?与其他语言相比，这种类型的类有哪些优缺点?

I was just reading the Python documentation about classes; it says, in Python "classes themselves are objects". How is that different from classes in C#, Java, Ruby, or Smalltalk? What advantages and disadvantages does this type of classes have compared with those other languages?

推荐答案

在Python中，类是对象，从某种意义上讲，您可以像分配其他对象一样将它们分配给变量，将它们传递给函数等.例如

In Python, classes are objects in the sense that you can assign them to variables, pass them to functions, etc. just like any other objects. For example

>>> t = type(10)
>>> t
<type 'int'>
>>> len(t.__dict__)
55
>>> t() # construct an int
0
>>> t(10)
10

Java具有 Class 对象，这些对象提供有关类的一些信息，但是您不能使用它们代替显式的类名.它们不是真正的类，而只是类信息结构.

Java has Class objects which provide some information about a class, but you can't use them in place of explicit class names. They aren't really classes, just class information structures.

Class C = x.getClass();
new C(); // won't work

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