python __call__ 函数
__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
[*]
[]
[*]
'''
页:
[1]