A plugin is some PHP code that:
- lives in phpwiki/lib/plugin/<pluginname>.php
- implements the WikiPlugin interface by extending that class.
There are many plugins already distributed with PhpWiki. Simply look in the lib/plugin directory or see the PluginManager list or see all the Help/*Plugin pages.
To write your own, look at the 
Help:HelloWorldPlugin (HelloWorld.php
in that directory), which is a minimal example of a plugin.
Publish your self-written plugin at a new PhpWiki page with
PluginName + Plugin appended
and add a link to CategoryContributedPlugin.
A WikiPlugin allows one to easily add new types of dynamic content (as well as other functionality) to wiki pages within PhpWiki. In this very wiki all actions which are not entirely lowercased are implemented using plugins, and some lowercased convenience actions also. (rename, revert, setacl, diff, ...)
Note that you can NOT extend the markup syntax with a plugin, as in other wiki engines.
(The old-style MagicPhpWikiURLs have been replaced by plugins
entirely.)
Example
Currently, one invokes a plugin by putting something like:
<<AllPages limit=20 cols=3>>
into a regular wiki-page. That particular example produces a list
of the first 20 existing pages in 3 columns, via the PageList
library.
Details
Plugins can take certain named arguments, most do. The values of these arguments can be determined four different ways. In order of precedence:
The plugin invocation can specify the value for an argument, like so:
<?plugin BackLinks page=OtherPage ?>
The argument can be specified via an HTTP query argument. This doesn't happen (is not allowed) unless the argument is mentioned in the plugin invocation:
<?plugin BackLinks page ?>
Default values specified in the plugin invocation:
<?plugin BackLinks page||=OtherPage ?>
The plugin must supply default values for each argument it uses. Such default args may be overriden by URL arguments like so:
BackLinks?page=ThisPage&sortby=-mtime
(The BackLinks plugin uses the current page as the default value for the page argument.)
Most plugins using the
PageList library inherit their
default arguments from the PageList.
Standard Arguments
Most plugins display a list of pages, via the PageList
library. PageList provides automatic support for those arguments.
info, exclude, author, owner, creator, sortby, limit, paging, cols, azhead, comma, commasep, ordered
For details see the
exclude and pages accept a list of pages. Either as comma-seperated list,
supporting glob-style wildcards, or via the <!plugin-list pluginname [args] !>
invocation syntax, where pluginname might be any plugin returning a PageList.
See PhpWiki:PluginList.
Since most plugins return a PageList, this PageList is also a common input parameter for other plugins, actions or formats.
Basic Plugin Types
All these plugins derive from the WikiPlugin class extending the run method, which returns a object tree of HTML objects, and may react on any provided arguments from the WikiPage (see the args below) or optionally overridden by arguments from the url (GET or POST args), if defined via '||='.
A basic plugin just needs the run() method, and optionally getName,
getDescription, getDefaultArguments. See the
Help:HelloWorldPlugin for a short introduction.
plugin reacts on its arguments and the request and displays arbitrary HTML.
plugin-form is used to display a input type=text box for the default argument s.
plugin-list is used as argument to provide a dynamic list of pagenames.
<?plugin PluginName [args...] ?><?plugin-form PluginName [args...] ?><?plugin PluginName args=<!plugin-list pluginname [args...] !> ?>
The box Method
Themes based on the "sidebar" theme may use the box method of any plugin, which displays a title and a condensed content in a box.
WikiPluginCached
Plugins deriving from the class WikiPluginCached must also define the methods getPluginType(), optionally getExpire(), managesValidators(), and dependent of the getPluginType the methods to display the possibly cached result.
getImage(), getMap() or getHtml(),
optionally also
getAlt(), getImageType(), embedMap(), embedImg(), embedObject()
See the config.ini PLUGIN_CACHED_* settings and PhpWiki:WikiPluginCached
Action Pages
The term ActionPage refers to a page containing a plugin
invocation with the same or translated pluginname as the pagename.
An action is together with the pagename argument the basic
PhpWiki argument.
It can both be GET or POST actions. Actions are untranslated, always
English, pagenames can be localized.
Basic (and old) actions are all lowercase, like edit, browse, remove, ...
Newer actions in PhpWiki:CamelCase are invoked via plugins on their
specific action page.
We decoupled actions from plugins via action pages for the following reasons:
- Support translated action buttons and customizable action descriptions.
- Customize standard actions by tuning the plugin invocation arguments. Override or add plugin defaults.
- Split simple plugins into multiple actions, like RecentChanges/RecentEdits, MostPopular/LeastPopular, AllPages/AllPagesCreatedByMe/AllPagesLastEditedByMe/ AllPagesOwnedByMe which differ only in one argument.
- Simplify the syntax for actions on another actions using a PageList as result of an actionpage as input parameter for another action or format.
- Those actions which have buttons or links in the theme or are referenced in the standard pgsrc pageset require their (possibly localized) actionpages, otherwise the actions will not work.
- If the localized actionpage is not found the english version is used.
- If no actionpage is found, it is recommended to do action=upgrade, which imports all missing and required action pages into the database.
So for a hypothetical new MyActionPage plugin MyActionPage will invoke the plugin and Help:MyActionPagePlugin should be the description page.
Existing Plugins
See PluginManager for a detailed list. Most plugins should have their own description page as subpage of Help/ with the name Plugin appended.
Contributed Plugins
See PhpWiki:CategoryContributedPlugin.