my $pat = qr/\w+ ((w)hit(e)|(b)lac(k))/;

    $_ = 'mostly black';
    my($word, $first, $last) = grep defined $_, /$pat/;
    print "$word starts with $first and ends with $last\n" if $word;

    $_ = 'but some white spaces';
    ($word, $first, $last) = grep defined $_, /$pat/;
    print "$word starts with $first and ends with $last\n" if $word;