This note regards page specific variables described here:
https://www.pmwiki.org/wiki/PmWiki/PageVariables
It is a suggestion to consider a minor addition to the
Custom page variables section to add an example of using
a user-defined function to construct a value to assign to
a custom page variable.
My task involved finding a way to keep two (almost) wiki
sites consistent during a transition period using only
periodic rsync of the master wiki to a temporary replica.
Both domain and http vs. https changes occurred. The
main challenge was that some wiki content used hard-coded
http://... URLs to other areas of the web space outside
the wiki but on the same server. These links broke when
rsyncing updates to a different server. I hoped not to
change rendered content simply because I was moving the
wiki to a new platform, and envisioned using computed
variables that could be used in place of the hard-coded
URLs.
Use of custom page variables appeared viable, but I found
it difficult to gain understanding of syntax rules that
apply to defining a Page Variable via a moderately
complex expression. I tried a number of simple syntax
structures with intermittent success though each time I
tried to modify the simple examples, the change would
invariably break some syntax rule I was not able to
discern.
In the end, by looking at various cookbook files, I found
a function call assignment syntax structure that worked
immediately and completely removed complexity of syntax.
So much time was spent trying to get other syntax forms
to work that it seems a documentation change could help
others if it showed an example using a user-function to
assign the FmtPV value.
Without meaning to imply that the following example is
without fault, the following illustrates the format:
function BaseURL()
{
$URLPrefix = "http";
if (! empty($_SERVER['HTTPS']))
{
if($_SERVER['HTTPS'] == 'on')
{
$URLPrefix .= "s";
}
}
return $URLPrefix .= "://" . $_SERVER['HTTP_HOST'] . "/Wiki";
}
$FmtPV['$BaseURL'] = 'BaseURL()';
It seems it could be helpful if the custom page variable
documentation mentioned a function call example as it has
a very simple syntax and allows for complex computation of
values to assign. Even if understanding of the existing
documentation is due to my own issues, perhaps I am not
alone and there are others who might benefit from adding
an example like this.
I placed this code in config.php and made a handful of changes
to replace hard coded URL text with {$BaseURL} references on a
few affected wiki pages (though the code could have been placed
in a cookbook PHP file included by config.php as cookbook files
normally are).
I am willing to edit the wiki myself to add a short example
(probably without full text of the user-function) if it does
not create a synchronization issue for other language pages
I cannot edit, or, if this is seen as undesirable, to simply
let this mailing list note suffice to put the information
out there for others.
--
Kevin R. Bulgrien
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