如何从其 try catch 块内部中断 for 循环？

Question

我正在尝试找到一种方法来摆脱这个 for 循环如果 try except 块内的代码块（在 for 循环内）成功执行，并且不调用异常。

这是对我不起作用的代码：

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        avar = afunc(attempt)
        break
    except KeyError:
        pass
        if attempt == attempts[-1]:
            raise KeyError

因为在I15成功执行后，它仍在尝试列表中调用J15项

这里的代码：

    except KeyError:
        pass
        if attempt == attempts[-1]:
            raise KeyError

如果代码已经在attempts中尝试了整个attempt，则用于抛出实际异常

Answer 1

您需要for … else 概念：https://docs.python.org/3/tutorial/controlflow.html#break-and-continue-statements-and-else-clauses-on-loops

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        avar = afunc(attempt)
    except KeyError:
        # error, let's try another item from attempts
        continue
    else:
        # success, let's get out of the loop
        break
else:
    # this happens at the end of the loop if there is no break
    raise KeyError

Answer 2

我相信最干净的方法是在 except 块内的 continue 和紧随其后的 breaking。在这种情况下，您甚至不必使用avar（除非我误解了问题）。

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        afunc(attempt)
    except KeyError:
        continue
    break

如果您确实需要avar 以供以后使用：

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        avar = afunc(attempt)
    except KeyError:
        continue
    break
print(avar) # avar is a available here, as long as at least one attempt was successful