my($openokay) = open(MW,"+<$filename"); 

    if (!$openokay) {
        return 0;
    }

##</code><code>##

open(MW,"+<$filename") || return 0;

# Or even...
sub fileopen {
my ($filename) = shift;
if ( open(MW,"+<$filename") ) {
     lock(*MW);
     seek(MW,0,0);
     return *MW;
} else {
     return 0;
}