## <a name="TWiki_Plugins"> TWiki Plugins </a>

Plugins allow you to extend the syntax or functionality of TWiki. ...

[[TWikiPreferences]] has the list of installed plugins and activated plugins.

### <a name="How_to_Create_a_Plugin"> How to Create a Plugin </a>

under construction... ( check back at <http://TWiki.org/cgi-bin/view/TWiki/TWikiPlugins> )

### <a name="How_to_Install_a_Plugin"> How to Install a Plugin </a>

under construction... ( check back at <http://TWiki.org/cgi-bin/view/TWiki/TWikiPlugins> )

### <a name="Plugins_under_the_hood"> Plugins under the hood </a>

* All plugin modules that exist in the `lib/TWiki/Plugins` directory are activated automatically unless disabled by the `DISABLEDPLUGINS` preferences variable in [[TWikiPreferences]]. You can optionally list the installed plugins in the `INSTALLEDPLUGINS` preferences variable. This is useful to define the sequence of plugin execution, or to specify other webs then the %WIKITOOLNAME% web for the plugin topics. Settings in [[TWiki/TWikiPreferences]]:
  * <code>Set INSTALLEDPLUGINS = DefaultPlugin, ...</code>
  * <code>Set DISABLEDPLUGINS = EmptyPlugin, ...</code>

* The <code>%ACTIVATEDPLUGINS%</code> variable shows all currently activated plugins. This variable is shown in [[TWiki/TWikiPreferences]] for debug reasons.

* Search order for plugin topics: Full `web.topicname` name is used if specified in `INSTALLEDPLUGINS`, then the %TWIKIWEB% web is searched, then the current web.

* Plugin specific settings are done in individual plugin topics. Two settings are standard for each plugin:
  * One line description, used to form the bullets describing the plugins in the [[TWiki/TextFormattingRules]] topic:
    * `Set SHORTDESCRIPTION = Blah blah.`
  * Debug plugin, output can be seen in `data/debug.txt`: (Se to 0 or 1)
    * `Set DEBUG = 0`
  * The settings can be retrieved as preferences variables like `%<pluginname>_<var>%`, i.e. <code>%DEFAULTPLUGIN\_SHORTDESCRIPTION%</code> shows the description of the DefaultPlugin.

* The <code>%PLUGINDESCRIPTIONS%</code> variable shows a bullet list with descriptions of all currently activated plugins. This variable is based on `%<plugin>_SHORTDESCRIPTION%` preferences variables of individual topics and is shown in [[TWiki/TextFormattingRules]].

-- [[Main/PeterThoeny]] - 14 Jul 2001 <br />