python __str__ & __repr__ & __cmp__

For ( __str__ ),we going to see a example …

and find who is working for …

#!/usr/bin/pythonclass Person(object):    def __init__(self,name,gender):
        self.name = name
        self.gender = genderif __name__ == '__main__':    p = Person('Frank',23)
    print p

See,The instance of ( Person ) have a default method ,just like ( describe method ) …

it’s called by instance self (here,is p itself) …

So,what it is name …

keep read,you will find what’s it is …

#!/usr/bin/pythonclass Person(object):    def __init__(self,name,gender):
        self.name = name
        self.gender = gender    def __str__(self):
    　　 """override the object method"""
        return 'Person object: %s,%d' % (self.name,self.gender)if __name__ == '__main__':    p = Person('Frank',23)
    print p

See,we got a totally different result …

So,we know who is the method ( __str__ ) …

Okay,next we will talk (__cmp__) inside method …

#!/usr/bin/pythonclass Student(object):    def __init__(self,name,score):
        self.name = name
        self.score = score    def __str__(self):
        return '(%s: %s)' % (self.name,self.score)    __repr__ = __str__    def __cmp__(self,s):
        if self.score > s.score:
            return -1        elif self.score < s.score:
            return 1        else:
            if self.name < s.score:
                return -1
            elif self.name < s.name:
                return 1
            else:
                return 0if __name__ == '__main__':
    L = [Student('Tim',99),Student('Bob',88),Student('Alice',99)]
    print sorted(L)