Re: Re: Re: 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");
[download]

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");
[download]

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

Comment on Re: Re: Re: Am I missing something here? Select or Download Code

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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";` [download] 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` [download] 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).	[reply] [d/l] [select]
Re: (lestrrat) Do use 'constant': Re(4): Am I missing something here? by Biker (Priest) on Nov 09, 2001 at 01:18 UTC
And Biker humbly bowes his head in respect. Amen. f--k the world!!!! /dev/world has reached maximal mount count, check forced.	[reply]
Re4: Am I missing something here? by blakem (Monsignor) on Nov 08, 2001 at 00:47 UTC
`*DEBUG=\1;` [download] would probably be more clear as: `use constant DEBUG => 1;` [download] -Blake	[reply] [d/l] [select]
Re: Re4: Am I missing something here? by Biker (Priest) on Nov 08, 2001 at 01:44 UTC
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.	[reply]
Re: Re: Re4: Am I missing something here? by suggus (Sexton) on Nov 08, 2001 at 02:15 UTC
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	[reply]


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