How to better write multiple exceptions with redundant code in Python?

问题

How can I better write the following snippet in Python:

try:
    statement-1
except Exception1:
    codeblock-1
    codeblock-2
except Exception2:
    codeblock-2

Just to be clear, I want to execute two codeblocks when the first exception occurs, while only the latter of these two codeblocks when the second exception occurs.

回答1:

You have two options, as I see it; either:

1. Extract codeblock-2 into a function and just call it (you repeat only one line this way); or
2. Catch both exceptions in the same except, then handle the two cases appropriately by checking the type of the caught exception.

Note that these aren't mutually exclusive, and the second approach is probably more readable if combined with the first. A snippet of the latter:

try:
    statement-1
except (Exception1, Exception2) as exc:
    if isinstance(exc, Exception1):
        codeblock-1
    codeblock-2

In action:

>>> def test(x, y):
    try:
        return x / y
    except (TypeError, ZeroDivisionError) as exc:
        if isinstance(exc, TypeError):
            print "We got a type error"
        print "We got a type or zero division error"


>>> test(1, 2.)
0.5
>>> test(1, 'foo')
We got a type error
We got a type or zero division error
>>> test(1, 0)
We got a type or zero division error

回答2:

I would just straightforwardly use local function:

def exception_reaction():
    codeblock2()

try:
    statement1()
except Exception1:
    codeblock1()
    exception_reaction()
except Exception2:
    exception_reaction()

来源：https://stackoverflow.com/questions/30235188/how-to-better-write-multiple-exceptions-with-redundant-code-in-python