Python中有趣在__call__函数_Python

Python中有趣在__call__函数

2020-07-17 10:30Python教程网 Python

这篇文章主要介绍了Python中有趣在__call__函数,本文直接给出一个使用实例,以此来讲解__call__函数的用法,需要的朋友可以参考下

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

									[]

									'''