初识python魔法函数

 1 # -*- coding: utf-8 -*-
 2 
 3 
 4 class myTest1(object):
 5     def __init__(self, argv1):
 6         ‘‘‘ myTest1 init ‘‘‘         # help()函数打印的帮助信息
 7         self.argv1 = argv1
 8 
 9     def __len__(self):
10         ‘‘‘ myTest1 length ‘‘‘
11         return len(self.argv1)
12 
13     def __str__(self):
14         ‘‘‘ myTest1 str help ‘‘‘
15         return "myTest1 __str__"
16 
17     def __repr__(self):          # __str__存在的时候，直接打印类会被覆盖
18         ‘‘‘ myTest1 repr help ‘‘‘
19         return "myTest1 __repr__"
20 
21     def __bool__(self):
22         ‘‘‘ myTest1 bool ‘‘‘
23         return isinstance(self.argv1, list)
24 
25 
26 if __name__ == "__main__":
27     run = myTest1("Hello world")
28     print(len(run))
29     print(run)
30     print(repr(run))
31     print(bool(run))
32     help(run)