This one had me stumpted. subrule(s /,/) is just a macro for <leftop: subrule /,/ subrule>, and so subrule(s? /,/) is just a macro for <leftop: subrule /,/ subrule>(?). However, internally, I think that leftop goes through another level, and so @arg must get overwritten. (that's just a guess as to what is happening, so don't take it as fact.) Anyways, whatever P::RD is doing internally, I would classify it as a bug.

However, just telling you that its a bug isn't really helping you, so here is a workaround: 

my $parser = new Parse::RecDescent (q[
    functiondefine: /function/i name "(" parameters[$item[1]](?) ")" "
+{"
    name:           /[A-Za-z][a-zA-Z0-9_]*/
    parameters:     parameter[$arg[0]] ',' parameters[$arg[0]] { [@ite
+m[1,3]] }
                  | parameter[$arg[0]] { [$item[1]] }
    parameter:      name /as/i variabletype { [@item[1..$#item]] }
    variabletype:   /variant|array|keyarray/i
]);

[download]

This is much more inefficent then using <leftop:> would be, but at least it works (at least as far as I've tested it.) I also collapsed your variabletype rule into a single regex, which will be much more efficient.

In reply to Re: Problem with Parse::RecDescent and subrule arguments by jryan
in thread Problem with Parse::RecDescent and subrule arguments by richard5mith

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