解決方法覆蓋for循環中的局部變量？

Question

我的代碼是這樣的：

funcs = [] 

class NumberContainer(): 
    def __init__(self, num): 
     self.number = num 

items = [] 
for i in range(5): 
    items.append(NumberContainer(i+1)) 

for item in items: 
    number = item.number 
    n = number 
    def my_func(x): 
     res = x < n 
     print("is {} less than {}? {}".format(x, number, res)) 
     return res 
    funcs.append(my_func) 

for f in funcs: 
    f(3) 

此輸出：

is 3 less than 5? True 
is 3 less than 5? True 
is 3 less than 5? True 
is 3 less than 5? True 
is 3 less than 5? True 

但很明顯，我真正想要的是它來檢查數字的範圍。

我該如何做到這一點？

Answer 1

解決方案（通常情況下）是不使用全局變量（或非本地變量）。你的函數的輸入應該來自參數，輸出應該是返回值。至於構建功能我會用某種廠..

在這種情況下，我會寫：

def comparison_factory(compare_to): 
    def compare_func(x): 
     res = x < compare_to 
     print("is {} less than {}? {}".format(x, compare_to, res)) 
     return res 
    return compare_func 

funcs = [ comparison_factory(n) for n in range(1,5) ] 

for f in funcs: 
    f(3)