ikiwiki plugins are written in perl. Each plugin is a perl module, in
the IkiWiki::Plugin
namespace. The name of the plugin is typically in
lowercase, such as IkiWiki::Plugin::inline
. Ikiwiki includes a
IkiWiki::Plugin::skeleton
that can be fleshed out to make a useful
plugin. IkiWiki::Plugin::pagecount
is another simple example.
Note
One thing to keep in mind when writing a plugin is that ikiwiki is a wiki compiler. So plugins influence pages when they are built, not when they are loaded. A plugin that inserts the current time into a page, for example, will insert the build time. Also, as a compiler, ikiwiki avoids rebuilding pages unless they have changed, so a plugin that prints some random or changing thing on a page will generate a static page that won't change until ikiwiki rebuilds the page for some other reason, like the page being edited.
Registering plugins
Plugins should, when imported, call IkiWiki::hook to hook into ikiwiki's processing. The function uses named parameters, and use varies depending on the type of plugin being registered. Note that a plugin can call the function more than once to register multiple hooks. All calls to IkiWiki::hook should be passed a "type" parameter, which gives the type of hook, a "id" paramter, which should be a unique string for this plugin, and a "call" parameter, which is a reference to a function to call for the hook.
Writing a PreProcessorDirective
This is probably the most common use of a plugin.
IkiWiki::hook(type => "preprocess", id => "foo", call => \&preprocess);
Replace "foo" with the command name that will be used inside brackers for the preprocessor directive.
Each time the directive is processed, the referenced function (preprocess
in the example above) is called, and is passed named parameters. A "page"
parameter gives the name of the page that embedded the preprocessor
directive. All parameters included in the directive are included as named
parameters as well. Whatever the function returns goes onto the page in
place of the directive.
Error handing
While a plugin can call ikiwiki's error routine for a fatal error, for errors that aren't intended to halt the entire wiki build, including bad parameters passed to a PreProcessorDirective, etc, it's better to just return the error message as the output of the plugin.
Html issues
Note that if the htmlscrubber is enabled, html in PreProcessorDirective output is sanitised, which may limit what your plugin can do. Also, the rest of the page content is not in html format at preprocessor time. Text output by a preprocessor directive will be passed through markdown (or whatever engine is used to htmlize the page) along with the rest of the page.
Other types of hooks
Beyond PreProcessorDirectives, Other types of hooks that can be used by plugins include:
checkconfig
IkiWiki::hook(type => "checkconfig", id => "foo", call => \&checkconfig);
This is useful if the plugin needs to check for, or modify ikiwiki's configuration. It's called early in the ikiwiki startup process. The function is passed no values. It's ok for the function to call IkiWiki::error if something isn't configured right.
filter
IkiWiki::hook(type => "filter", id => "foo", call => \&filter);
Runs on the raw source of a page, before anything else touches it, and can
make arbitrary changes. The function is passed named parameters page
and
content
and should return the filtered content.
htmlize
IkiWiki::hook(type => "htmlize", id => "ext", call => \&filter);
Runs on the raw source of a page and turns it into html. The id parameter specifies the filename extension that a file must have to be htmlized using this plugin. This is how you can add support for new and exciting markup languages to ikiwiki.
pagetemplate
IkiWiki::hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
Each time a page is rendered, a template is filled out.
This hook allows modifying that template. The function is passed the name
of the page, and a HTML::Template
object that is the template that will
be used to generate the page. It can manipulate that template, the most
common thing to do is probably to call $template->param() to add a new
custom parameter to the template.
sanitize
IkiWiki::hook(type => "sanitize", id => "foo", call => \&sanitize);
Use this to implement html sanitization or anything else that needs to modify the content of a page after it has been fully converted to html. The function is passed the page content and should return the sanitized content.
delete
IkiWiki::hook(type => "delete", id => "foo", call => \&dele);
Each time a page or pages is removed from the wiki, the referenced function is called, and passed the names of the source files that were removed.
change
IkiWiki::hook(type => "change", id => "foo", call => \&render);
Each time ikiwiki renders a change or addition (but not deletion) to the wiki, the referenced function is called, and passed the names of the source files that were rendered.
cgi
IkiWiki::hook(type => "cgi", id => "foo", call => \&cgi);
Use this to hook into ikiwiki's cgi script. Each registered cgi hook is called in turn, and passed a CGI object. The hook should examine the parameters, and if it will handle this CGI request, output a page and terminate the program.
Wiki configuration
A plugin can access the wiki's configuration via the %IkiWiki::config
hash. The best way to understand the contents of the hash is to look at
ikiwiki.setup, which sets the hash content to configure the wiki.
Wiki data
If your plugin needs to access data about other pages in the wiki. It can use the following hashes, using a page name as the key:
%IkiWiki::links
lists the names of each page that a page links to, in an array reference.%IkiWiki::pagemtime
contains the last modification time of each page%IkiWiki::pagectime
contains the creation time of each page%IkiWiki::renderedfiles
contains the name of the file rendered by a page%IkiWiki::pagesources
contains the name of the source file for a page.%IkiWiki::depends
contains a GlobList that is used to specify other pages that a page depends on. If one of its dependencies is updated, the page will also get rebuilt.Many plugins will need to add dependencies to this hash; the best way to do it is by using the IkiWiki::add_depends function, which takes as its parameters the page name and a GlobList of dependencies to add.
RCS plugins
ikiwiki's support for revision control systems also uses pluggable perl
modules. These are in the IkiWiki::RCS
namespace, for example
IkiWiki::RCS::svn
.
Each RCS plugin must support all the IkiWiki::rcs_* functions. See IkiWiki::RCS::Stub for the full list of functions. It's ok if rcs_getctime does nothing except for throwing an error.
See about RCS backends for some more info.