ikiwiki/doc/todo/plugin.mdwn

A plugin system should ideally support things like:

* [[todo/lists]] of pages, of mising pages / broken links (done), orphaned
  pages (done), of registered users, etc
* a [[todo/link_map]]
* [[todo/sigs]] ?
* [[pageindexes]]
* Wiki stats, such as the total number of pages (done), total number of links, most linked to pages, etc, etc.
* wiki info page, giving the ikiwiki version etc
* would it be useful to reimplement the hyperestradier search integration as a plugin?
* Support [[RecentChanges]] as a regular page containing a plugin that updates each time there is a change, and statically builds the recent changes list. (Would this be too expensive/inflexible? There might be other ways to do it as a plugin, like making all links to RecentChanges link to the cgi and have the cgi render it on demand.)
* Support for smileys or other symbols. I appreciate the support for check
  marks, etc in other wikis.
* For PlaceWiki I want to be able to do some custom plugins, including one
  that links together subpages about the same place created by different
  users. This seems to call for a plugin that applies to every page w/o any
  specific marker being used, and pre-or-post-processes the full page
  content. It also needs to update pages when related pages are added,
  so it needs to register dependencies pre-emptively between pages,
  or something. It's possible that this is a special case of backlinks and
  is best implemented by making backlinks a plugin somehow. --[[Joey]]
* etc
* For another type of plugin, see [[todo/PluggableRenderers]].

Another, separate plugin system that already (mostly) exists in ikiwiki is
the RCS backend, which allows writing modules to drive other RCS systems
than subversion.

## case study: Moin Moin plugins

See <http://moinmoin.wikiwikiweb.de/MoinDev/PluginConcept>

6 different types of plugins:

* *actions* are possibly out of scope for ikiwiki, this is probably what it uses for cgi script type stuff. Unless ikiwiki wants to allow pluggable CGI script stuff, it doesn't need these.
* *parsers* and *formatters* are basically what I've been calling [[PluggableRenderers]]. MoinMoin separates these, so that a page is parsed to (presumbly) some intermediate form before being output as html or some other form. That's a nice separation, but what to do about things like markdown that are both a parser and a formatter?
* *macros* and *processors* are analagous to preprocessor directives. A processor can operate on a large block of text though.
* *themes* should be irrellevant (ikiwiki has [[templates]]).