如何在python的一个块中编写多个try语句？

Question

我想要做：

try:
    do()
except:
    do2()
except:
    do3()
except:
    do4()

如果do（）失败，则执行do2（），如果do2（）也失败，则执行do3（），依此类推。

最好的祝福

Answer 1

我first()为此编写了一个快速包装函数。

用法 ：value = first([f1, f2, f3, ..., fn], default='All failed')

#!/usr/bin/env


def first(flist, default=None):

    """ Try each function in `flist` until one does not throw an exception, and
    return the return value of that function. If all functions throw exceptions,
    return `default`

    Args: 
        flist - list of functions to try
        default - value to return if all functions fail

    Returns:
        return value of first function that does not throw exception, or
        `default` if all throw exceptions.

    TODO: Also accept a list of (f, (exceptions)) tuples, where f is the
    function as above and (exceptions) is a tuple of exceptions that f should
    expect. This allows you to still re-raise unexpected exceptions.
    """

    for f in flist:
        try:
            return f()
        except:
            continue
    else:
        return default

# Testing.

def f():
    raise TypeError

def g():
    raise IndexError

def h():
    return 1


# We skip two exception-throwing functions and return value of the last.
assert first([f, g, h]) == 1

assert first([f, g, f], default='monty') == 'monty'