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在函數裡嵌套函數，嵌套函數如果使用到了外面的變量，則使用的是外面函數棧中的變量，相當於是淺復制一份給內函數，直到外函數執行結束才會復制一份給內函數
def fun_list():
fun_list=[]
for i in range(1,10):
print('the id of i is:',id(i))
def fun():
''' 定義用到i，i是fun_list2()內存中的i，改變了i的值函數打印的也會變 '''
print('I have got number %d, '%i,'its id is:',id(i))
fun()
print('a new fun() is defined')
fun_list.append(fun)
''' 函數執行結束時，才會把i復制傳遞給之前定義的各個fun() '''
return fun_list
fun_list=fun_list()
print('------------------------')
for i in range(len(fun_list)):
fun_list[i]()
運行結果
the id of i is: 1652060816
I have got number 1, its id is: 1652060816
a new fun() is defined
the id of i is: 1652060848
I have got number 2, its id is: 1652060848
a new fun() is defined
the id of i is: 1652060880
I have got number 3, its id is: 1652060880
a new fun() is defined
the id of i is: 1652060912
I have got number 4, its id is: 1652060912
a new fun() is defined
the id of i is: 1652060944
I have got number 5, its id is: 1652060944
a new fun() is defined
the id of i is: 1652060976
I have got number 6, its id is: 1652060976
a new fun() is defined
the id of i is: 1652061008
I have got number 7, its id is: 1652061008
a new fun() is defined
the id of i is: 1652061040
I have got number 8, its id is: 1652061040
a new fun() is defined
the id of i is: 1652061072
I have got number 9, its id is: 1652061072
a new fun() is defined
------------------------
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
I have got number 9, its id is: 1652061072
Process finished with exit code 0
再舉一個例子：
def func():
i=1
print('The number of i is: %d now'%i)
def i_printer():
print('Hello! The number of i is %d'%i)
for i in range(2,10):
print('The number of i is: %d now'%i)
i_printer()
return i_printer
func()
雖然i_printer()在for之前就定義了，但是此是它裡面使用的i是func()的棧裡面的i，i變了打印的內容就會變，我們運行一下
The number of i is: 1 now
i_printer: The number of i is: 2 now
Hello! The number of i is 2
i_printer: The number of i is: 3 now
Hello! The number of i is 3
i_printer: The number of i is: 4 now
Hello! The number of i is 4
i_printer: The number of i is: 5 now
Hello! The number of i is 5
i_printer: The number of i is: 6 now
Hello! The number of i is 6
i_printer: The number of i is: 7 now
Hello! The number of i is 7
i_printer: The number of i is: 8 now
Hello! The number of i is 8
i_printer: The number of i is: 9 now
Hello! The number of i is 9
解決方案
def fun_list():
fun_list=[]
for i in range(1,10):
print('the id of i is:',id(i))
def new_fun(i):
''' 解決方案：在外面再嵌套一層函數，把內層函數用到的外層參數傳給它，然後在裡面定義內函數，把內層函數作為返回值，調用這個函數來定義內層函數 '''
def fun():
''' 定義用到i，i是fun_list2()內存中的i，改變了i的值函數打印的也會變 '''
print('I have got number %d, '%i,'its id is:',id(i))
return fun
print('a new fun() is defined')
fun_list.append(new_fun(i))
''' new_fun執行結束時，必須把i深復制給它的內層函數fun() '''
return fun_list
fun_list=fun_list()
print('------------------------')
for i in range(len(fun_list)):
fun_list[i]()
the id of i is: 1652060816
a new fun() is defined
the id of i is: 1652060848
a new fun() is defined
the id of i is: 1652060880
a new fun() is defined
the id of i is: 1652060912
a new fun() is defined
the id of i is: 1652060944
a new fun() is defined
the id of i is: 1652060976
a new fun() is defined
the id of i is: 1652061008
a new fun() is defined
the id of i is: 1652061040
a new fun() is defined
the id of i is: 1652061072
a new fun() is defined
------------------------
I have got number 1, its id is: 1652060816
I have got number 2, its id is: 1652060848
I have got number 3, its id is: 1652060880
I have got number 4, its id is: 1652060912
I have got number 5, its id is: 1652060944
I have got number 6, its id is: 1652060976
I have got number 7, its id is: 1652061008
I have got number 8, its id is: 1652061040
I have got number 9, its id is: 1652061072
Process finished with exit code 0
