On 3/6/06, Tom Allison <[EMAIL PROTECTED]> wrote:
>
> I ran into a potential problem when writing some code this weekend.
>
> I'm running a network socket to pick up data and then run it against a
> database connection before I return the response. Essentially it falls
> into a few steps:
>
> read from network
> read from database
> write to database
> do something else on network
> write to network
>
> Being the cautious code writer I thought it would make sense to use
> something like:
>
> eval{
> alarm(10);
> "read from network"
> "read from database"
> ....
> }
>
> But each of these database calls has it's own eval{} around the database
> query (as an example):
> my $rv;
> eval {
> $rv = $dbh->do($sql) or die $!;
> };
> if ( $@) {
> die "[EMAIL PROTECTED]"
> } else {
> return $rv;
> }
>
> Which essentially means if I flattened out all the subroutines I would
> end up with something like
>
> eval {
> ...
> eval {....}
> if ($@) { }
> eval { ... }
> if ($@) {...}
> }
> if ($@) {
> .....}
>
> The problem I run into is throwing the exceptions up to the top eval{}
> structure when I need to communicate that something didn't work right
> so I can provide feedback to the network client connection.
>
> I suppose I could try and rewrite the code to un-nest the eval{}
> statements but I think that is avoiding learning something I should know
> about how to manage eval{} for block exception handling.
>
> Is there some way to rethrow or propogate errors or some tips on how to
> manage this better?
>
die on errors and just keep passing them up the line:
eval {
eval {
eval {
bad_system_call() or die "$!\n";
} or die $@;
} or die $@;
};
print "eval says: [EMAIL PROTECTED]" if $@;
As long as you keep propagating $@ in your die calls, the original
error message will get passed out.
HTH,
-- jay
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