You still can't PreCompile that. You're forcing the calling script to parse the parser's grammar, generate the parser code and compile the parser code everytime it runs. That's extremely slow, so that's something you only want to do when the grammar is changed.

To achieve that goal, start by making make_grammar.pl as follows:

use strict;
use warnings;

use Parse::RecDescent ();

my $szGrammar = <<'__END_OF_GRAMMAR__';

    {
        use strict;
        use warnings;

        use constant DEBUG => 1;

        use Data::Dumper;

        sub AddToHash {
            print "MyParser->AddToHash(@_)\n" if (DEBUG);
            my ($this, $szVar, $szValue) = @_;

            $this->{Result}->{$szVar} = $szValue;
        }

        sub GetResult {
            print "MyParser->GetResult(@_)\n" if (DEBUG);
            my ($this) = @_;

            return $this->{Result};
        }

        sub DumpResult {
            print "MyParser->DumpResult(@_)\n" if (DEBUG);
            my ($this) = @_;

            print Dumper($this->{Result});
        }
    }

    test: expr(s) /^\Z/

    expr: name '=' /\d+/
        {
            $thisparser->AddToHash($item{name}, $item[-1]);
        }

    name: /\w+/

__END_OF_GRAMMAR__

Parse::RecDescent->PreCompile($szGrammar, 'MyParser')
   or die("Bad Grammar\n");
[download]

You run the above once, then you use it as follows:

use strict;
use warnings;

use MyParser ();

my $hParser = MyParser->new();
my $szCode = "x = 1\ny = 2\nz = 3";
$hParser->test($szCode)
   or die("Bad code\n");
$hParser->DumpResult();
[download]

I still stand by my earlier note: I prefer the solution I posted earlier because it doesn't break if backtracking occurs like this one does.

I'd also like to add that <<'__END_OF_GRAMMAR__' ... __END_OF_GRAMMAR__ has fewer issues than q{ ... }.