Python中有一个有趣的语法,只要定义类型的时候,实现__call__函数,这个类型就成为可调用的。
换句话说,我们可以把这个类型的对象当作函数来使用,相当于 重载了括号运算符。
class g_dpm(object): def __init__(self, g): self.g = g def __call__(self, t): return (self.g*t**2)/2
计算地球场景的时候,我们就可以令e_dpm = g_dpm(9.8),s = e_dpm(t)。
class Animal(object): def __init__(self, name, legs): self.name = name self.legs = legs self.stomach = [] def __call__(self,food): self.stomach.append(food) def poop(self): if len(self.stomach) > 0: return self.stomach.pop(0) def __str__(self): return 'A animal named %s' % (self.name) cow = Animal('king', 4) #We make a cow dog = Animal('flopp', 4) #We can make many animals print 'We have 2 animales a cow name %s and dog named %s,both have %s legs' % (cow.name, dog.name, cow.legs) print cow #here __str__ metod work #We give food to cow cow('gras') print cow.stomach #We give food to dog dog('bone') dog('beef') print dog.stomach #What comes inn most come out print cow.poop() print cow.stomach #Empty stomach '''-->output We have 2 animales a cow name king and dog named flopp,both have 4 legs A animal named king ['gras'] ['bone', 'beef'] gras [] '''
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