python闭包学习笔记四

#coding:utf-8

'''闭包作用：封装、代码复用.>>>>>>>闭包存放函数的方式'''
#def my_sum(*arg):
#    if len(arg) == 0:
#        return 0
#    for val in arg:
#        if not isinstance(val, int):
#            return 0
#    return sum(arg)
#
#def my_average(*arg):
#        if len(arg) == 0:
#            return 0
#        for val in arg:
#            if not isinstance(val, int):
#                return 0
#        return sum(arg) / len(arg)
#
#print my_sum(1, 2, 3, 4, 5)
#print my_average(1, 2, 3, 4, 5)
#print my_sum('22')
#print my_average(1, 2, 3, 4, 5, '33')

def my_sum(*arg):
print "in_my_sum=",arg
return sum(arg)

def my_average(*arg):
print "my_average=",arg
return sum(arg) / len(arg)
#在该函数中返回了in_dec,而在in_dec中又引用了func，所以func被放入in_dec的属性中
def dec(func):
def in_dec(*arg): ## func函数会被放入in_dec的属性中引用了func
print "in_dec arg=",arg
if len(arg) == 0:
return 0
for val in arg:
if not isinstance(val, int):
return 0
return func(*arg)
return in_dec

'''my_sum == in_dec(*arg)'''
my_sum = dec(my_sum)
my_average = dec(my_average)
'''先执行in_dec，再执行func'''

print my_sum(1, 2, 3, 4, 5)
print my_average(1, 2, 3, 4, 5)
print my_sum('22')
print my_average(1, 2, 3, 4, 5, '33')