doc/todo/conditional_text_based_on_ikiwiki_features.mdwn



I'd like to see some way to conditionally include wiki text based on whether the wiki enables or disables certain features.  For example, [[helponformatting]], could use \[[if (enabled smiley) """Also, because this wiki has the smiley plugin enabled, you can insert \[[smileys]] and some other useful symbols."""]], and a standard template for [[plugins]] pages could check for the given plugin name to print "enabled" or "disabled".
Some potentially useful conditionals:

enabled pluginname
disabled pluginname
any pagespec: true if any of the pages in the [[PageSpec]] exist
all pagespec: true if all of the pages in the [[PageSpec]] exist
no pagespec or none pagespec: true if none of the pages in the [[PageSpec]] exist
thispage pagespec: true if pagespec includes the page getting rendered (possibly one including the page with this content on it).
sourcepage pagespec: true if pagespec includes the page corresponding to the file actually containing this content, rather than a page including it.
included: true if included on another page, via [[plugins/inline]], [[plugins/sidebar]], [[plugins/contrib/navbar]], etc.

You may or may not want to include boolean operations (and, or, and not); if you do, you could replace disabled with not enabled, and no pagespec or none pagespec with not any pagespec (but you may want to keep the aliases for simplicity anyway).  You also may or may not want to include an else clause; if so, you could label the text used if true as then.
Syntax could vary greatly here, both for the [[PreprocessorDirective]] and for the condition itself.