Hi Mark --
> I was just working with CGI::App today and ran into a situation I've
> run into several times before: I got an internal server error
> because a
> template could not be found when load_tmpl() was called. It would be
> nice if CGI::App could systematically address this issue by providing
> some error handling for this case. Here's a specific proposal to do
> that:
The problem you describe is a classic one of exception handling. Perl is
notoriously bad at exception handling. Since there is no universal
"exception handling system" in Perl, many people have tried to roll their
own. I would prefer not to go down that path.
In lieu of rolling an exception-handling system, I have tried to implement
the behavior which is valid for most people most of the time. Most of the
time, failure to locate a template is a fatal error. Templates are,
generally, statically assigned. If a programmer types "serch_form.tmpl"
instead of "search_form.tmpl", it seems sensible to die(). The programmer
has made a typo, and the program has a bug as a result.
If, OTOH, you have devised a system where users specify templates (via a
form text field, for instance), it will not do to die(). Clearly, you need
some other type of handling for this exception. Fortunately, the
object-oriented nature of CGI::Application makes it easy for you to roll
your own. By simply overriding the load_tmpl() method, you can do whatever
you like:
package MyCGIApp;
use base q/CGI::Application/;
sub load_tmpl {
my $self = shift;
my ($tmpl_file, @extra_params) = @_;
my $t;
eval {
require HTML::Template;
$t = HTML::Template->new_file($fq_tmpl_file, @extra_params);
};
if ($@) {
# We got an error!
$self->param('TMPL_ERROR' => $@);
return undef;
} else {
# Everything is OK!
$self->param('TMPL_ERROR' => '');
return $t;
}
}
FWIW, it is not CGI::Application which is die()-ing when you specify a bad
template -- it is HTML::Template. If Perl had an exception handling system,
HTML::Template would throw a "not found" error, and your app could catch it.
As it is, you have to just live with it, or catch it in an eval block, as I
have illustrated.
TTYL,
-Jesse-
----
Jesse Erlbaum, CTO
Vanguard Media
212.242.5317 x115
[EMAIL PROTECTED]
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