The reason for other recommendations is that this scheme makes debugging an all or nothing mechanism. When I was working on a very complex system with many classes, I needed a way to get run-time information from the classes of interest, without clogging output completely with the full range of feedback I'd coded into the system. For that I used an initialization that parsed out which classes should spit out run-time information, then went on the specialize it more so that the instances associated with certain tables would have debugging on, while others were off.

One disadvantage to using a global variable is that it is prone to typos. If your code refers to $main::DEBYG somewhere you'll have to catch it yourself; it's a valid variable name.

Also, you can shorten your modifiers:

if $self->{DEBUG}
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if ($self->{DEBUG})
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sub dbg {
  my ($self,$msg) = @_;
  return if (! $self->{_debug});
  print STDERR "[DEBUG] : $msg\n";
}
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sub debug {
  my ($self,$val) = @_;
  $self->{_debug} = $val if (defined $val);
  $self->{_debug};
}
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sub dbg {
  my $msg = shift;
  print "[DEBUG] : $msg\n" if ($main::DEBUG);
}
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You can do something like:

package My::WunderCode;
BEGIN {
    if(  $ENV{DEBUG_MY_WUNDERCODE}  ) {
        eval "sub debug() { !1 }";
    } else {
        eval "sub debug() { 1 }";
    }
    die $@   if  $@;
}
warn "Debugging ",__PACKAGE__,"...\n"   if  debug;
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Question... I am new to perl(about a month or so) and i have finished the Learning Perl for Win32...where else, in your opinion, should i go to further my learning for perl in retrospect to being able to apply it on my NT/2k machines. I bought "Windows NT - Win32 Perl Programming: The Standard Extensions" and it is a little more advanced in programming. Maybe i guess...i am looking for...something that will keep going in progression...kinda like how the Learning Perl book does...learn a little something new and test my knowledge on it with everything that i previously learned as well. I am able to apply scripts that i find or other people provide for me as examples by tweeking them, but i probably would not be able to get there by myself. Does that make sense? This may be a lot of jarble..but since you do program for NT/2k environment, i figured you would be a good person to ask. Any advice would be much appreciated. As i am always open to listen. thnx ~Ray

That is, if package Deb prints reams of debugging information when $main::DEBUG is set, you might find it useful in debugging to say

package Deb;

sub frob {
  # do stuff...
  print_debugging_info if $main::DEBUG;
  # do more stuff...
}
# ...


package main;

$::DEBUG = undef;      # usually don't want debugging information

my $deb1 = new Deb (...);
my $deb2 = new Deb (...);

# do stuff with $deb1, $deb2, but no debugging information

{
  local $::DEBUG = 1;  # buggy bit

  $deb1->frob(42);
  $deb2->nitz(17);
}

# no more debugging output

# ...
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local is usually a very good match for various logs.

A better approach IMHO is to have a centralized messaging/logging/debugging method or function that takes a message and a priority number, and use that in your code instead of calling print().

Then you can set the debugging level (e.g., with an environment variable, or a configuration option, or even just an option or an argument), and if the current debugging level exceeds or is equal to the priority number of a message, the message will be printed to STDERR, or logged to a file, or whatever.

Christian Lemburg
Brainbench MVP for Perl
http://www.brainbench.com

I was looking at Devel::Messenger this morning. It looks like it does this. You can have debug levels and print certain messages only if debugging is on or above that level. It will print to files\filehandles as well. I haven't tried it yet though.

Error: Keyboard not attached. Press F1 to continue.

For production servers on Unix, a good idea is to use Sys::Syslog. On Windows, the equivalent would be Win32::EventLog.

Christian Lemburg
Brainbench MVP for Perl
http://www.brainbench.com