初识python魔法函数

python魔法函数主要是针对类

 

# -*- coding: utf-8 -*-


class myTest1(object):
    def __init__(self, argv1):
        ''' myTest1 init '''         # help()函数打印的帮助信息
        self.argv1 = argv1

    def __len__(self):
        ''' myTest1 length '''
        return len(self.argv1)

    def __str__(self):
        ''' myTest1 str help '''
        return "myTest1 __str__"

    def __repr__(self):          # __str__存在的时候，直接打印类会被覆盖
        ''' myTest1 repr help '''
        return "myTest1 __repr__"

    def __bool__(self):
        ''' myTest1 bool '''
        return isinstance(self.argv1, list)


if __name__ == "__main__":
    run = myTest1("Hello world")
    print(len(run))
    print(run)
    print(repr(run))
    print(bool(run))
    help(run)

输出信息：

11

myTest1 __str__

myTest1 __repr__

False

 

Help on myTest1 in module __main__ object:

 

class myTest1(builtins.object)

 |  myTest1(argv1)

 |

 |  Methods defined here:

 |

 |  __bool__(self)

 |      myTest1 bool

 |

 |  __init__(self, argv1)

 |      myTest1 init

 |

 |  __len__(self)

 |      myTest1 length

 |

 |  __repr__(self)

 |      myTest1 repr help

 |

 |  __str__(self)

 |      myTest1 str help

 |

 |  ----------------------------------------------------------------------

 |  Data descriptors defined here:

 |

 |  __dict__

 |      dictionary for instance variables (if defined)

 |

 |  __weakref__

 |      list of weak references to the object (if defined)

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