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title: Python
date: 2020-08-09 14:24:25
updated: 2020-09-20 18:23:03
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### 一、python类的实例方法、静态方法和类方法区别及其应用场景
[https://blog.csdn.net/helloxiaozhe/article/details/79940321](https://blog.csdn.net/helloxiaozhe/article/details/79940321)
### 二、python 中cls和self的区别
self：指的是一个具体实例的本身。如果在class中的某个方法加了@classmethod修饰器，那么这个方法不需要实例化也能直接被其他程序调用。
cls：表示这个类本身。
[https://blog.csdn.net/gtf215998315/article/details/106868558](https://blog.csdn.net/gtf215998315/article/details/106868558)
### 三、list.extend()和list.append()
>>> li = ['a', 'b', 'c']  
>>> li.extend(['d', 'e', 'f'])   
>>> li   ['a', 'b', 'c', 'd', 'e', 'f']  
>>> len(li)                      
6  
>>> li[-1]  'f'   >>> li = ['a', 'b', 'c']  
>>> li.append(['d', 'e', 'f'])   
>>> li   ['a', 'b', 'c', ['d', 'e', 'f']]  
>>> len(li)                      
4  
>>> li[-1]   ['d', 'e', 'f']