python - 如何解决 UnboundLocalError？

Question

我刚开始编程并尝试写一些东西但(当然)它失败了。在我找到真正的问题之后:UnboundLocalError。因此，为了让您远离周围的所有废墟，我将代码简化为:

def test():
    try:
        i1 = int(i1)
        i2 = int(i2)
    except ValueError:
        print "you failed in typing a number"

def input(): 
    i1 = raw_input('please type a number \n >')
    i2 = raw_input('please type a number \n >')

然后我写下:

>>>input()
please insert a number
> 3
please insert a number
> 2 
>>>test()

然后我得到:

that was not a number
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 7, in test
UnboundLocalError: local variable 'i1' referenced before assignment

我怎样才能用 Pythonic 的方式解决这个问题？还是我应该采取完全不同的方式？

Answer 1

执行此操作的最标准方法是为您的测试方法提供参数:

def test(i1, i2):
    try:
        i1 = int(i1)
        i2 = int(i2)
    except ValueError:
        print "you failed in typing a number"

def input(): 
    i1 = raw_input('please type a number \n >')
    i2 = raw_input('please type a number \n >')
    test(i1, i2)   # here we call directly test() with entered "numbers"

如果你真的想在交互式提示上进行测试，你可以这样做(如@FerdinandBeyer 评论中所建议的那样):

def test(i1, i2):
    try:
        i1 = int(i1)
        i2 = int(i2)
    except ValueError:
        print "you failed in typing a number"
    return i1, i2
    
def input(): 
    i1 = raw_input('please type a number \n >')
    i2 = raw_input('please type a number \n >')
    return i1, i2

然后，根据提示:

>>>var1, var2 = input()
please insert a number
> 3
please insert a number
> 2 
>>>test(var1, var2)