`IkiWiki::Plugin::skeleton` that can be fleshed out to make a useful
plugin. `IkiWiki::Plugin::pagecount` is another simple example.
-## Note
+# 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
change until ikiwiki rebuilds the page for some other reason, like the page
being edited.
-## Registering plugins
+# Registering plugins
-Plugins should, when imported, call IkiWiki::register_plugin to hook into
-ikiwiki. The function takes four parameters:
+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.
-1. A method type. Use "preprocess" to register a [[PreProcessorDirective]]
-2. A command name. This is the bit that will appear inside brackets in a
- page.
-3. A reference to a subroutine that is run when the plugin is used.
+# Writing a [[PreProcessorDirective]]
-## Writing a [[PreProcessorDirective]]
+This is probably the most common use of a plugin.
-For preprocessor commands, the subroutine is passed named parameters. A
-"page" parameter gives the name of the page that embedded the preprocessor
-command. All parameters included in the preprocessor command are included
-as named parameters as well. Whatever the subroutine returns goes onto the
-page in place of the command.
+ IkiWiki::hook(type => "preprocess", id => "foo", call => \&preprocess);
-## Error handing in plugins
+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, while a "destpage" parameter gices the name of the page the
+content is going to (different for inlined pages). 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
## Html issues
-Note that if [[HTMLSanitization]] is enabled, html in
+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.
+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:
+
+## getopt
+
+ IkiWiki::hook(type => "getopt", id => "foo", call => \&getopt);
+
+This allows for plugins to perform their own processing of command-line
+options and so add options to the ikiwiki command line. It's called during
+command line processing, with @ARGV full of any options that ikiwiki was
+not able to process on its own. The function should process any options it
+can, removing them from @ARGV, and probably recording the configuration
+settings in %IkiWiki::config. It should take care not to abort if it sees
+an option it cannot process, and should just skip over those options and
+leave them in @ARGV.
+
+## 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 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 (or part of a blog page, or an rss feed) is rendered, a
+[[template|templates]] is filled out. This hook allows modifying that
+template. The function is passed named parameters. The "page" and
+"destpage" parameters are the same as for a preprocess hook. The "template"
+parameter is a `HTML::Template` object that is the template that will be
+used to generate the page. The function can manipulate that template
+object.
+
+The most common thing to do is probably to call $template->param() to add
+a new custom parameter to the template. Note that in order to be robust,
+it's a good idea to check whether the template has a variable before trying
+to set it, as setting a variable that's not present is an error.
+
+ if ($template->query(name => 'foo')) {
+ $template->param("foo" => "bar");
+ }
+
+## sanitize
-## Wiki configuration
+ IkiWiki::hook(type => "sanitize", id => "foo", call => \&sanitize);
-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
+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
+# 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 is linked to from that page in an array reference.
+ 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::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.
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.
+
+# A note on generating html links
+
+Many plugins need to generate html links and add them to a page. This is
+done by using the `IkiWiki::htmllink` function. The usual way to call
+htmlllink is:
+
+ htmllink($page, $page, $link)
+
+Why is $page repeated? Because if a page is inlined inside another, and a
+link is placed on it, the right way to make that link is actually:
+
+ htmllink($page, $destpage, $link)
+
+Here $destpage is the inlining page. A destpage parameter is passed to some
+of the hook functions above; the ones that are not passed it are not used
+during inlining and don't need to worry about this issue.
+
+# 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.