Re: Question on goto with try/catch
* TVisitor:
A project I am working on has large amounts of code written in this
style:
void MyClass::MyFunction()
{
try
{
// code here
if(something bad happened)
goto label;
}
catch(...)
Don't catch by ellipsis unless you're rethrowing (and possibly picking up the
exception again, but anyway rethrowing) within the catch handler.
For example, consider a badly designed exception that is a pointer to a
dynamically allocated exception object, like in Microsoft's MFC.
You wouldn't want to leak that.
{
// exception handling here.
}
label:
// Run cleanup code - deallocate memory, etc.
}
Mixed curse levels.
Redundancy.
Personally, I would rather throw an exception instead of the goto, let
the catch do it's thing, and then the regular cleanup code will
execute.
An alternative that's easier to get right is to use a scopeguard (it's a RAII
based thingy).
Check out Petru Marginean & Andrei Alexandrescu's ScopeGuard article in some old
DDJ issue, available on the net.
However, for your "deallocate memory", simply do not do that manually. Even a
scopeguard is too low level for "deallocate memory". Use standard containers and
perhaps smart pointers if needed, or garbage collection if that's your thing.
However, from a "does it work?" standpoint, what are the implications
of using a goto to jump out of a try? Does it leave some uncleaned up
stuff behind (i.e. on the stack), or does it work properly, however
inelegant it looks?
Works properly, but is as noted mixing curse levels and redundant.
Please realize I'm don't wish to start an
unstructured looking code holy war, I'm questioning operation so I can
decide whether or not I need to rewrite this *now* or put it on a to-
do list for a later date. I'm not a big fan of rewriting code that
works - however inelegant - if it's been around and doing it's job.
If it works don't fix it.
Cheers & hth.,
- Alf
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