|Just another Perl shrine|
Re: Best Practices for Exception Handlingby jonadab (Parson)
|on Jan 30, 2003 at 04:21 UTC||Need Help??|
> Robustness. I can forget to check for an returned error value.
> I cannot forget to check for an exception.
> Brevity. I prefer: $o->foo->bar->fribble->ni
> to $o->foo or return(ERROR_FOO); [snip]
Huh? Error return codes? Error return codes are basically an inelegant way of doing exactly the same thing -- punting the problem to some other code someplace else. It's that whole approach that I don't understand the value of. Points one, two, and five all seem to be arguing against return codes, which are in my view basically a certain (particularly inelegant) type of exception handling. You don't need to convince me that's a bad way to do it; my question is why it (punting an error to the caller's caller's caller) should ever be done at all.
Regarding your third point, clarity: one of us is smoking crack, because putting code that handles an error pages away from where the error actually happens is my idea of severe obfuscation. How it could ever conceivably enhance clarity is entirely beyond my ability to fathom.
Point four, however, I'd like to explore further. Maybe I just haven't encountered the right problem yet. Every error I've had to handle either could be fixed, or it couldn't. If it couldn't be fixed, it either could be logged and ignored and the program proceed less certain functionality, or else it was fatal. That basically leaves three options when an error condition pops up: do stuff to fix the problem, log it and go on, or spit an error message and exit. I have yet to encounter a situation where the caller might be relevant to the question of which of these conditions applies.
So, back to your point four: can you suggest a real-world example or two of a situation where the error needs to be handled differently depending on where the routine is called or other circumstances not known to the code that finds the error? I've been through this discussion before (not here) and have tried to imagine such a situation, but I can't seem to come up with one.