[pmwiki-users] processing order

[marc]

Peter & Melodye Bowers said...
> > Peter & Melodye Bowers said...
> > > Is there any kind of situation in which directives (like markup
> > expressions)
> > > get processed twice in a single browse of a page?  Or (more surprising)
> > that
> > > echo statements could somehow be suppressed during an earlier invocation
> > of
> > > the MX?
> > 
> > Have you followed the instructions from:
> > 
> >   /PmWiki/CustomMarkup
> > 
> > The problem might also stem from the format of the content you are
> > returning to PmWiki - whether it is markup, a directive, HTML, etc. -
> > where Keep($result) might be necessary.
 
> I have confirmed that the markup expression I am working is indeed being
> called twice.  I had to put debugging statements in including microtime()
> output and run it on a slower computer to be able to catch (via a quick
> printscreen) a flash of debugging (echo) output.  This flashes by (on the
> slow computer -- too fast to catch on a faster computer) and is immediately
> replaced by almost identical debugging output.

Rather than using echoes - which are generally fine - have a look at 
error_log(). Might help your sanity ;-) Alternatively, write a debug 
recipe that writes to a wiki page; that's the method I use for sites, 
with notify on the page to email those interested.

Something like this should get you started (I think it will work in 
PHP4; I've tried to strip out the PHP5 stuff that I use):

# singleton, use PmWikiError::getInstance()->postError(...);
Class PmWikiError {

  var $pageName;

  function PmWikiError($pagename) {
    $this->pageName = $pagename;
  }
  function getInstance ($pagename='Site.ScriptErrors') { 
    static $pmwikierr = null;
    if (! isset($pmwikierr) )
      $pmwikierr = new PmWikiError($pagename);
    return $pmwikierr;
  }	
  function postError($error) {
    global $Now, $IsPagePosted, $FarmD;
    include_once("$FarmD/scripts/notify.php");
    $page = ReadPage($this->pageName);
    $page['text'] = strftime('%a, %d %b %y @ %H:%M:%S', $Now)."\\\\\n".
$error."\n\n".$page['text'];
    WritePage($this->pageName,$page);
    $IsPagePosted = true;
    PostNotify($this->pageName,$page,$page);
  }	
}

> By carefully comparing the
> microtime() timestamps on my printscreen version to the final version it is
> clear that they are 2 separate invocations.  I then put debugging in
> MarkupExpression() (in scripts/markupexpr.php) with the same sort of
> microtime() debugging and confirmed that MarkupExpression() itself is being
> called twice.
> 
> Any idea how this could happen?  How do echo statement outputs get cleared
> from a screen?

Redirect()? 

> How does MarkupExpression() get called multiple times when
> there's only one call?  I'm sure it's something I'm doing, but I don't have
> a clue where to look...
> 
> Is it possible that pmwiki might process through a page once and then "look"
> at the output of that run-through again to see if there are any further
> markups that need to be processed recursively?  I'm shooting in the dark
> here, but that would make sense if that's what it does...  (I don't see any
> markup in the results -- I'm coming up with a pretty blank page actually,
> but at least it would give me something to point at...)

It sounds like Redirect() behaviour to me.

-- 
Cheers,
Marc