$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";
    }
}
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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.

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?

Yup.

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/ };
    }
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cheers.

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.

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";
}
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