Re: Re: trapping -w warnings

What Zaxo doesn't provide, is a working example. So, here is one, tailored to your snippet:

$re = '[\w-]';
my @warnings;
{
    local $SIG{__WARN__} = sub { push @warnings, shift };
    eval {'' =~ /$re/ };
}
if($@) {
    print "error: $@\n";
} else {
    foreach my $warning (@warnings) {
        print "Got a warning: $warning";
    }
}
[download]

Alternatively, you can do your checking inside the $SIG{__WARN__} sub.

Note how you need a semicolon after some "blocks" for it to work: after the assignment of the anonymous sub to $SIG{__WARN__}, and after the eval block, at least if any statement comes right after it — which you forgot.

Comment on Re: Re: trapping -w warnings Download Code

Replies are listed 'Best First'.
Re: Re: Re: trapping -w warnings by Anonymous Monk on Nov 26, 2003 at 07:44 UTC
Perfect. Thanks to both of you. I gather that the effect of "local" as used here is to restore the original handler upon exiting the block?	[reply]
Re: Re: Re: Re: trapping -w warnings by bart (Canon) on Nov 26, 2003 at 07:49 UTC
Yup.	[reply]
Re^3: trapping -w warnings by tphyahoo (Vicar) on Nov 24, 2006 at 13:54 UTC
I liked this enough that I bookmarked this in my delicious collection -- helped me debug a nasty problem. I did things slightly differently though -- more localized, I think. `{ local $SIG{__WARN__} = sub { my @warnings = @_; foreach my $warning (@warnings) { print "got a warning: $warning\n"; } }; eval {'' =~ /$re/ }; }` [download] cheers.	[reply] [d/l]
Re^4: trapping -w warnings by bart (Canon) on Nov 24, 2006 at 18:47 UTC
AFAIK `$SIG{__WARN__}` is only ever called with one parameter: the current warning. So your loop is most likely useless. You can print each warning as it comes along. But what I did was collect the warnings first so you can print them out as a block. That may be useful if you want just one block, for example when printing warnings in a HTML page on a web server.	[reply] [d/l]
Re^4: trapping -w warnings by tphyahoo (Vicar) on Feb 20, 2007 at 15:28 UTC
On second thought, I don't think I needed that eval block. This works fine too. `use strict; use warnings; { local $SIG{__WARN__} = sub { my @warnings = @_; foreach my $warning (@warnings) { warn "in handleEncoding, got a warning: $warning\n"; } }; warn "blee"; warn "blah"; warn "bloo"; }` [download]	[reply] [d/l]