use Interpolation;
tie %HTML, "Interpolation", \&escape;  # works with global or with lexical: my %HTML
{
    my %esc;
    BEGIN {
        %esc = ( '&' => '&amp;', '<' => '&lt;',
          '>' => '&gt;', '"' => '&quot;',   # if you want them
        );
    }
    sub escape {
        my $s = pack 'U0a*', shift;
        $s =~ s/([&<>"])/$esc{$1}/g;
        $s =~ s/([^\0-\x7F])/$esc{$1} ||= '&#' . ord($1) . ';'/ge;
        return $s;
    }
}