Re: Re: Conditional compilation

You can always call a function with a DEBUG flag and execute certain parts if it's set or not. Thank you, Micah Gersten onShore Networks Internal Developer http://www.onshore.com Robert Cummings wrote: > On Fri, 2008-08-15 at 18:34 -0500, Shawn McKenzie wrote: > >> Herman Gomez wrote: >> >>> Hi, >>> >>> Here is something I used to do in C/C++ to include/exclude automaticaly >>> all debugging code at compiling time: >>> >>> #define debug TRUE >>> #ifdef(debug) >>> //debugging code >>> #endif >>> >>> That way I can include/exclude easily all debugging code in the final >>> compiled code. In PHP I have not been able to find anything like that. >>> The only solution I've found is having this kind of code in every debug >>> code block: >>> >>> if ($debug) { >>> //debugging code >>> } >>> >>> But this means that the debugging code is in the final compiled >>> (interpreted) code, wasting cpu cycles even if there won't be any >>> debugging in production. >>> >>> Does somebody know if there is something like conditional compilation in >>> PHP that I can use? >>> >>> Regards, >>> Herman Gomez >>> Madrid, Spain. >>> >> Well PHP isn't compiled it's interpreted. Still I don't see much diff >> and no overhead between the following: >> >> #ifdef(debug) >> //debugging code >> #endif >> >> ---and--- >> >> if (defined('DEBUG')) { >> //debugging code >> } >> >> I don't think checking a define is cpu intensive or even measurable. >> You could "assume" that it's defined as true or false and: >> >> if (DEBUG === true)) { >> //debugging code >> } >> >> Still, I don't think that even checking $debug is measurable. >> > > That depends on where the conditional exists. In C you can place it > anywhere, including wihtin a tight loop. In PHP you end up having to > either take an overhead penalty or duplicate code to force the > conditional outside of a tight loop. > > Contrast the following: > > <?php > > if( DEBUG === true ) > { > for( $i = 0; $i < 1000000; $i++ ) > { > // Do something common between DEBUG and !DEBUG modes. > // Do something dependent on debug mode. > } > } > else > { > for( $i = 0; $i < 1000000; $i++ ) > { > // Do something common between DEBUG and !DEBUG modes. > } > } > > ?> > > Versus: > > <?php > > for( $i = 0; $i < 1000000; $i++ ) > { > // Do something common between DEBUG and !DEBUG modes. > > if( DEBUG === true ) > { > // Do something dependent on debug mode. > } > } > > ?> > > Now depending on what "Do something common between DEBUG and !DEBUG > modes" does, it can be a real PITA to do code duplication to optimize > debug mode handling, but on the other hand, you really don't want to > check if DEBUG is enabled 1 million times. > > If I recall though... a few years ago the answer to this question was > that there's no reason why you can't use the C pre-processor to > accomplish the same thing with PHP. The down side though is that then > you lose debugging information such as the real line number on which an > error occurs. > > Cheers, > Rob. >