Interpolating variables in a Parse::RecDescent regex - perl

Question

I'm working on a Parse::RecDescent grammar to read a given human-readable set of rules and then spit out a file that is much easier for a computer to read.
One of the tokens is a list of "keywords"; about 26 different keywords. These may change over time, and may be referenced by multiple pieces of code. Consequently, I want to store the keyword-y things in a data file and load them in.
A feature of Parse::RecDescent is the ability to interpolate variables in regexes, and I would like to use it.
I wrote up some code as a proof of concept:
#arr = ("foo", "bar", "frank", "jim");
$data = <<SOMEDATA;
This is some data with the word foo in it
SOMEDATA
$arrstr = join("|", #arr);
if($data =~ /($arrstr)/)
{
print "Matched $1\n";
}
else
{
print "Failed to match\n";
}
This worked correctly.
When I moved to my main program to implement it, I wrote:
{
my $myerror = open(FILE, "data.txt") or die("Failed to open data");
my #data_arr = <FILE>;
close FILE;
my $dataarrstr = join("|", #data_arr);
}
#many rules having nothing to do with the data array are here...
event : /($dataarrstr)/
{ $return = $item[1]; }
|
And at this point, I received this error from P::RD: ERROR (line 18): Invalid event: Was expecting /($dataarrstr)/.
I don't know why. Does anyone have any ideas that would serve to help me out here?
edit:
This is not a scoping issue- I've tried that. I've also tried the m{...} syntax.

Answer 1

After perusing documentation and a very similar question over at http://perlmonks.org/?node_id=384098, I worked out this solution.
event :/\w+/
{
$return = ::is_valid_event($item[1]);
}
| <error>
Outside the grammar -
#This manages the problem of not being able to interpolate the variable
#in the grammar action
sub is_valid_event {
my $word = shift #_;
if($word =~ /$::data_str/)
{
return $word;
}
else
{
return undef;
}
}