On Fri, 2008-08-15 at 22:56 -0500, Shawn McKenzie wrote:
> 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.
>
> Great! Then the answer is: wait, wait,
>
> write it in C!
Well PHP does have a great extension system so you can plug in your own
C code ;)
Cheers,
Rob.
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