__call__
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
- []
- '''