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
[]
\'\'\'