Re: mod_perl 2.0 globals question

Tom Schindl Thu, 27 May 2004 03:15:52 -0700

Nathanial P. Hendler wrote:

I'm not sure if this is a style or function question.  I'd like to have a
module called Debug.pm that has a variable in it that if set to '1' by
anything (main script, or other modules) will print debug messages.

Reading the Orielly "Practical mod_perl" I thought it was clear what I
needed to do, but I am finding it difficult.  The following works as one
file, but when I break the Debug part into its own file, the value of $D
just increments with every re-load...

#!/usr/local/bin/perl

use strict;
use warnings;
use CGI qw(:standard);
use Debug;

print header();

Debug::report('I should not see this line');
$Debug::D++;
Debug::report('I should see this line');
$Debug::D++;
Debug::report('This one too');

package Debug;
use strict;
use warnings;

use vars qw($D);
$D = 0;

sub report {
    my $string = shift;

    print "DEBUG ($D): $string<br>\n" if $D;
}

1;


Can anyone explain to me why I can't have a global variable when I put
Debug into its own file?

Well that's mod_perl. It will compile your script only once perl forked-process|thread (which means it also loads your Debug.pm only once) hence all global variables hold their value.

This means the following:
* you should see:
  ---------------8<---------------
  I should see this line
  This one too
  ---------------8<---------------
  when the request is served by new forked/thread process which has not
  already loaded your YourModule.pm.
* you should see :
  ---------------8<---------------
  I should not see this line
  I should see this line
  This one too
  ---------------8<---------------
  on any next request servered by *exactly this* apache-child.

What you could do:
* reset $Debug::D directly before print header()
  e.g. Debug::reset()
* make an object out of debug:
  e.g. $debug = new Debug(), $debug->increment_counter()
* use mod_perls logging capabilities.

Can anyone tell me how to accomplish what I'm after?

Do you want to increase/decrease verbosity or why are you incrementing $D????

Tom


Thanks,
Nathanial Hendler
Tucson, AZ USA
http://retards.org/

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Re: mod_perl 2.0 globals question

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