EAFP vs LBYL (was Re: A little disappointed so far)

[VanL]

Alex Martelli wrote:

>     try:
>         useappropriately(thefile)
>     except ItWasWrong, howwasitwrong:
>         dealwithwrongness()

My problem with this approach:

(cue dramatic music)
Our chief error is an IOError...IOError and OSError... Our two errors 
are IOErrors and OSErrors...and RuntimeErrors.... Our *three* errors are 
IOErrors, OSErrors, and RuntimeErrors...and an occasional 
MemoryError.... Our *four*...no... *Amongst* our errors....

I have a hard time catching all the appropriate exceptions that a 
function may throw, especially if useappropriately(thefile) is 
non-trivial.  Pure EAFP code sometimes ends up looking like this

try:
     useappropriately(thefile)
except IOError:
     dealwithIOError()
except OSError:
      dealwithOSError()
except RandomError:
      dealwithRandomError....

and you can *still* get bitten if you haven't anticipated all the ways 
in which things can go wrong.   (And I know about bare excepts... but 
having bare excepts in your code opens up its own kettle of worms.) If I 
really need something to work, I usually do both a pre-check (LBYL) as 
well as a just-in-case try-except, so that the number of places and ways 
in which the useappropriately() function can go wrong is minimized.

Am I seriously misguided here?

VanL