use Exception::Class ( 'MyException' => { description => '' } );

eval {
    MyException->throw( message => '' );
};
if ($@) {
    print "I see you, exception class (boolean)!\n";
}
else {
    print "Nothing to see here (boolean).\n";
}
if ( $@ ne '' ) {
    print "I see you, exception class (ne '')!\n";
}
else {
    print "Nothing to see here (ne '').\n";
}
__END__
I see you, exception class (boolean)!
Nothing to see here (ne '').