in reply to Re: Re: Am I missing something here?
in thread Am I missing something here?

This will allways call the Debug() sub. The overhead may or may not be a problem in your production systems, it all depends on how many times this call is executed.

Imagine a few thousand times per minute. (Or per second...)

I propose the alternative solution: 

$debug=1;
$debug&&print("Debug info...\n");

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The above should require less overhead. I've even read somewhere that Perl optimizes this so that the $debug&& doesn't have to evaluated, but unfortunately I can't find back the reference to that text. :-( Maybe some of the well educated Monks may chime in about that?

If there is no reason to change the value of $debug during execution, the following should be even smarter(?): 
*DEBUG=\1;
$DEBUG&&print("Debug info...\n");

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f--k the world!!!!
/dev/world has reached maximal mount count, check forced.

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(lestrrat) Do use 'constant': Re(4): Am I missing something here?
by lestrrat (Deacon) on Nov 08, 2001 at 23:09 UTC

    I'm sure your way is more efficient compared to calling a sub all the time, but I would definitely push for "use constant" in this scenario, especially if you're concerned with efficiency

    Suppose the following is in a file called "debug.pl":

    *DEBUG = \1;
use constant CONST_DEBUG => 1;
$DEBUG && print "foo\n";
CONST_DEBUG && print "bar\n";

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    They look pretty much the same, but you should see the output of perl -MO=Deparse debug.pl

    ## Output of perl -MO=Deparse on my machine with perl 5.6.1:
*DEBUG=\(1);
sub CONST_DEBUG() {
    package constant;
    $scalar;
}
print "foo\n" if $DEBUG; # <- $DEBUG must be evaluated each time
print "bar\n"; # <- there's no evaluation... just straight print()'ing

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    There you see that the second option gives you a literal print "bar\n" without needing to evaluate another variable.

    This is because of a couple of reasons: 1 - the perl compiler is smart enough to optimize away "real" constants... and 2 - *DEBUG = \1 is NOT a "real" constant. (You can always assign on top of *DEBUG if you so choose to).

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      And Biker humbly bowes his head in respect. Amen.

      f--k the world!!!!
      /dev/world has reached maximal mount count, check forced.

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Re4: Am I missing something here?
by blakem (Monsignor) on Nov 08, 2001 at 00:47 UTC
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      Blake, thanks for the "probably". Much appreciated. ;-)

      As always, TIMTOWTDI. I prefer my way, since I think it's clearer, but I 100% respect your different point of view. I do let out my thoughts on this elsewhere.

      Hopefully, the original poster has got several useful hints and tips for how to go forward.

      f--k the world!!!!
      /dev/world has reached maximal mount count, check forced.

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        Biker,

        Yes, I've gotten a little more help since I've never tried this kind of debugging before...it's kinda fun, but frustrating because I still can't figure it out...I'll keep trying though.

        Totally! Thanks for everyone's input. If it weren't for you guys, I'd still be stuck on "#!" :-)

        -Gus
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