Token Replacement

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I'm working on a engine that requires tokens. The code snippet below is self explanatory. I am trying to get the script to print out the value of $test_var. It is printing out $test_var as $ticket_price as oppose to $test_var as 2. Any suggestions?

#!/usr/bin/perl -w

$seller_state = "CA";
$token = "##ticket_price##";

$rule = "if(##seller_state## eq 'CA'){ ##ticket_price## = 2; }";
token_clean($rule);

eval $rule; warn $@ if $@;

$test_var = token_clean($token);

print "$test_var\n";                            #doesnt work
print "$ticket_price\n";                        #work

sub token_clean(){
  $_[0] =~ s/##(.+?)##/\$$1/g;
  return($_[0]);
}
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Re: Token Replacement by Aristotle (Chancellor) on Jun 18, 2002 at 04:51 UTC
You're mixing the scopes of your "rules" and your regular code, in that snippet - unless you really want that (why one would eludes me, but there may be good reason I cannot think of), you will probably run into huge headaches at some point with that approach. If you don't understand why I'm saying this, then I urge you for your own sanity (and/or that of the people who will have to work with your code after you) to stick to a tried a and true solution from the CPAN. Text::Template for example handles templates with embedded Perl code very well. Makeshifts last the longest.	[reply]
Re: Token Replacement by Anonymous Monk on Jun 18, 2002 at 00:22 UTC
figured out. had to put eval around variable to print	[reply]
(jeffa) Re: Token Replacement by jeffa (Bishop) on Jun 18, 2002 at 00:33 UTC
Well, i am glad you got it to work, but maybe, just maybe, this is not the best way to solve your problem. Me? I'd tackle it with a +200 CPAN module named Parse::RecDescent, but that's just me ... UPDATE: ... that is, if you are doing what i think you are doing ... what are you doing? That is some of the craziest Perl code i have seen in a while, FWIIW. I am impressed, i think ... jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply]
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