How to execute something if any exception happens

Question

A python newbie question: I need to do the following

try:
  do-something()
except error1:
  ...
except error2:
  ...
except:
  ...
#Here I need to do something if any exception of the above exception was thrown.

I can set a flag and do this. But is there a cleaner way of doing this?

Answer 1

You can do this with a nested try. The except block of the outer try should catch all exceptions. Its body is another try that immediately re-raises the exception. The except blocks of the inner try actually handle the individual exceptions. You can use the finally block in the inner try to do what you want: run something after any exception, but only after an exception.

Here is a little interactive example (modeled on Applesoft BASIC for nostalgia purposes).

try:
    input("]")  # for Python 3: eval(input("]"))
except:
    try:
       #Here do something if any exception was thrown.
       raise
    except SyntaxError:
       print "?SYNTAX",
    except ValueError:
       print "?ILLEGAL QUANTITY",
    # additional handlers here
    except:
       print "?UNKNOWN",
    finally:
       print "ERROR"

Answer 2

I just tried a couple different idea's out and it looks like a flag is your best bet.

• else suite is only called if there is no exception
• finally will always be called