# This code has been run through a basic smoke-test.

package My::Error::String;

use overload
    '""' => \&stringify,
    '0+' => \&boolify,
        fallback => 1;

sub new {
    my $class = shift;
    my $error = shift;

    bless \$error, $class;
}

sub stringify {
    my $self = shift;
    return $$self;
}

sub boolify {
    return;
}
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Then, when you want to use it, you'd do something like:

use My::Error::String;

sub func_with_error {
    if ($have_error) {
        return My::Error::String->new( "Have an error somewhere ..." )
+;
    }
}
[download]