python - 使变量有条件地全局

Question

假设我需要运行一个带有循环的函数，直到满足条件为止。为了使函数正常工作，我只允许在函数中返回一个值，但是一旦条件清除，我想将我执行的一些计算带入全局范围。我不允许使用 return 命令来执行此操作，因此我决定在 post 中全局化变量。这会发出警告，但似乎工作正常。这是最好的做事方式吗？

这是一个例子:

def check_cond(x,cond):
    return (x - cond,3)

def loop(x,func):
    relevant_value = 0
    while x > 0:
        local_expensive_calculation = 1 #use your imagination
        x = func(x,local_expensive_calculation)[0]
        relevant_value += func(x,local_expensive_calculation)[1]
        if x == 0:
            global local_expensive_calculation
    return relevant_value

x = 4
loop(x,check_cond)

#then do stuff with local_expensive_calculation, which is now global

Answer 1

这可能会稍微滥用系统，但您可以将变量设置为函数的属性，然后稍后通过该命名空间访问它:

def check_cond(x,cond):
    return (x - cond,3)

def loop(x,func):
    relevant_value = 0
    while x > 0:
        local_expensive_calculation = 1 #use your imagination
        x = func(x,local_expensive_calculation)[0]
        relevant_value += func(x,local_expensive_calculation)[1]
        if x == 0:
            loop.local_expensive_calculation = local_expensive_calculation
    return relevant_value

x = 4
loop(x,check_cond)

print loop.local_expensive_calculation