Mason and $@

rkg has asked for the wisdom of the Perl Monks concerning the following question:

Hi.

Mason scoping question. Here's a reduction that illustrates the issue:

Why does this work properly (that is, the error message is sent off to the component)

<html>
<body>
% eval { die "this is an error"; };
% if ($@) {
%   my $message = $@;
%   $m->comp('/comps/error.comp', message=> $message);
% }
</body>
</html>
[download]

But this does not work properly (a blank string is sent off the component)

<html>
<body>
% eval { die "this is an error"; };
% if ($@) {
%  $m->comp('/comps/error.comp', message=> $@);
% }
</body>
</html>
[download]

Thanks for any insight.

rkg

UPDATE

Ok, since (notice the quotes)

$m->comp('/comps/error.comp', message=> "$@");
[download]

does work properly, I'm wondering if the issue is Mason, or if $@ has magic properties...

is $@ a simple scalar, or something more?

Comment on Mason and $@ Select or Download Code

Replies are listed 'Best First'.
Re: Mason and $@ by Fletch (Bishop) on Jan 25, 2004 at 19:13 UTC
`$@` can be changed by any intermediate steps which happen to cause it to change. I can't think it's out of the question that some part of the component resolution code is using an `eval` which is succeeding and thus clearing it out. Like `$1` or `$!`, unless you can absolutely count on other code not doing something to change it your best bet's copying it (either explicitly or through stringifying it).	[reply] [d/l] [select]
Re: Mason and $@ by coec (Chaplain) on Jan 25, 2004 at 20:39 UTC
A stab in the dark here, but it would be useful to see what $@ contains. I'm thinking that it would be expected to get an error if $@ contains one or more spaces. Maybe a `print Data::Dumper $@` or similar?	[reply] [d/l]

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