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return_func.py
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63 lines (54 loc) · 1.41 KB
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'''
Created on Sep 6, 2016
@author: sheldonshen
'''
#1函数作为返回值
def calc_sum(*args):
ax = 0
for n in args:
ax = ax + n
return ax
def lazy_sum(*args):
def mysum():
ax = 0
for n in args:
ax=ax+n
return ax
return mysum;
print(calc_sum(1,2,3,4))
f = lazy_sum(1,2,3,4)
print(f)
print(f())
f1 = lazy_sum(1,2,3,4)
f2 = lazy_sum(1,2,3,4)
print(f1 == f2) #False
#2闭包
#我们在函数lazy_sum中又定义了函数sum，并且，内部函数sum可以引用外部函数lazy_sum的参数和局部变量，
#当lazy_sum返回函数sum时，相关参数和变量都保存在返回的函数中，
#这种称为“闭包（Closure）”的程序结构拥有极大的威力
def count():
fs=[]
for i in range(1,4):
def f():
return i * i
fs.append(f)
return fs
f1,f2,f3=count()
print(f1())#9
print(f2())#9
print(f3())#9
#返回闭包时牢记的一点是:返回函数不要引用任何循环变量后者后续会发生变化的变量
def count_refactor():
def f(j):
def g():
return j * j
return g
fs=[]
for i in range(1,4):
fs.append(f(i))#f(i)立刻被执行,因此i的当前值被传入f()
return fs
f1,f2,f3=count_refactor()
print(f1())#1
print(f2())#4
print(f3())#9
#返回一个函数时，牢记该函数并未执行，返回函数中不要引用任何可能会变化的变量