my $patternreadfromfile= q{do_what_i_want( $1, $2 )};

sub do_what_i_want {
    my ($one, $two) = @_;
    for ( $one, $two ) {
        s/\A.(.*).\z/$1/;
    }
    return qq{<h1 tag="$one">$two</h1>};
}

my $outpattern = $patternreadfromfile;