sub generateTr {
    my( $from, $to )= @_;
    my $sub= eval <<END;
        sub {
            my( \$copy )= \@_;
            \$copy =~ tr/\Q$from\E/\Q$to\E/;
            return \$copy;
        }
END
    die "$@" if $@;
    return $sub;
}

my $xlate= generateTr( "abc", "def" );
my $c= $xlate->( "abc leppard" );
# $c is now "def leppdrd"