声明A类和A()类有什么区别? [英] What's the difference between declaring `class A` and `class A()`?

问题描述

我们在python中定义类如下:

We define class in python as following:

class A:
    def x(self):
        print("In x")

但是我只是打错了字，它在python 3.7版的linux cli中成功执行了.在这里:

But i just made a typo and it executed successfully in linux cli with python version 3.7. Here it is:

class A():
    def x(self):
        print("In x")

这是什么意思?

推荐答案

您可以选择继承在Python中使用语法 class Child(Parent):从其他类中获取.括号中不留任何参数都与括号中留有相同:您只是从基类 object 继承而已，而没有别的什么.例如:

You can optionally inherit from other classes with the syntax class Child(Parent): in Python. Leaving no argument in the parenthesis is the same as leaving the parenthesis off: you just inherit from the base object class and nothing else. For example:

class A:
    pass

class B(object):
    pass

class C():
    pass

import inspect

inspect.getmro(A)
# (__main__.A, object)
inspect.getmro(B)
# (__main__.B, object)
inspect.getmro(C)
# (__main__.C, object)

所有等效项.作为反例:

All equivalent. As a counter-example:

class D(A):  # inherit from A
    pass

inspect.getmro(D)  # should include A now
# (__main__.D, __main__.A, object)

这篇关于声明A类和A()类有什么区别?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！