symbolic reference to variable in callers name space

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

I'm developing CGI's and modules for use under Apache with mod_perl. I would _like_ to have a module access the value of a variable in the callers package, namely $DEBUG.

$main::DEBUG works fine in the module when it is run from test.pl (make test). But when called from the CGI, it's undefined. OK, I looked at (caller)[0] (the callers package), which looks like (in my current project:
Apache::ROOTweb_2emgh_2eharvard_2eedu::dnacore::cgi_2dbin::synthesis::CE_QC</p>

So, since it will change, I thought I'd try to use the package name as a symbolic reference(slightly abridged):

my $pkg = (caller)[0];
no strict;
warn("${$pkg::DEBUG} in $pkg"); # see what it gets
[download]

Which was still undefined. But if I use the package string literally:
warn("$Apache::ROOTweb_2emgh_2eharvard_2eedu::dnacore::cgi_2dbin::synthesis::CE_QC::DEBUG in $pkg");

I get the value expected. I've thrashed around and skimmed the docs for a while now, trying different ways of bracketing, attempting to typeglob, etc. Now it's way past time I ate and I'm frustrated. Please, if anyone can help solve this, I would, as always, be very appriciative!

TIA,
Sean

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Re: symbolic reference to variable in callers name space by Fletch (Bishop) on Aug 06, 2002 at 17:11 UTC
ITYM `${"${pkg}::DEBUG"}`. `${$pkg::DEBUG}` is the variable named by the value contained in the variable `$DEBUG` in package `pkg`.	[reply] [d/l] [select]
Re: symbolic reference to variable in callers name space by danboo (Beadle) on Aug 06, 2002 at 18:05 UTC
for your warn example, i believe you want: `warn(${"${pkg}::DEBUG"} . " in $pkg"); # see what it gets` [download] - danboo	[reply] [d/l]
Re: Re: symbolic reference to variable in callers name space by spq (Friar) on Aug 07, 2002 at 14:23 UTC
Thank you both! That does indeed work. I did need to change: `warn("DEBUG = ${"${pkg}::DEBUG"} in $pkg");` [download] in my code (which threw a syntax error about missing bracket!?), to: `warn("DEBUG = " . ${"${pkg}::DEBUG"} . " in $pkg");` [download] Which did the trick for testing. Thanks again! Sean	[reply] [d/l] [select]