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。
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class g_dpm( object ):
def __init__( self , g):
self .g = g
def __call__( self , t):
return ( self .g * t * * 2 ) / 2
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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)。
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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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