function is passed no values. It's ok for the function to call
`error()` if something isn't configured right.
+### refresh
+
+ hook(type => "refresh", id => "foo", call => \&refresh);
+
+This hook is called just before ikiwiki scans the wiki for changed files.
+It's useful for plugins that need to create or modify a source page. The
+function is passed no values.
+
### needsbuild
hook(type => "needsbuild", id => "foo", call => \&needsbuild);
-This allows a plugin the manipulate the list of files that need to be
+This allows a plugin to manipulate the list of files that need to be
built when the wiki is refreshed. The function is passed a reference to an
array of pages that will be rebuilt, and can modify the array, either
adding or removing files from it.
called during the preliminary scan that ikiwiki makes of updated pages,
before begining to render pages. This parameter should be set to true if
the hook modifies data in `%links`. Note that doing so will make the hook
-be run twice per page build, so avoid doing it for expensive hooks.
+be run twice per page build, so avoid doing it for expensive hooks. (As an
+optimisation, if your preprocessor hook is called in a void contets, you
+can assume it's being run in scan mode.)
Note that if the [[htmlscrubber]] is enabled, html in
[[ikiwiki/PreProcessorDirective]] output is sanitised, which may limit what
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 (including the http headers) and
-terminate the program.
+parameters, and if it will handle this CGI request, output a page
+(including the http headers) and terminate the program.
+
+Note that cgi hooks are called as early as possible, before any ikiwiki
+state is loaded, and with no session information.
### auth
bypass it). When a page is edited, each registered canedit hook is called
in turn, and passed the page name, a CGI object, and a session object.
-If edit can proceed, the hook should return "". If the edit is not allowed
-by this hook, the hook should return an error message for the user to see.
If the hook has no opinion about whether the edit can proceed, return
-`undef`, and the next plugin will be asked to decide.
+`undef`, and the next plugin will be asked to decide. If edit can proceed,
+the hook should return "". If the edit is not allowed by this hook, the
+hook should return an error message for the user to see, or a function
+that can be run to log the user in or perform other action necessary for
+them to be able to edit the page.
+
+This hook should avoid directly redirecting the user to a signin page,
+since it's sometimes used to test to see which pages in a set of pages a
+user can edit.
### editcontent
add/remove/change fields, tweak the validation code for the fields, etc. It
will not validate or display the form.
-Form validation and display can be overridden by the formbuilder hook.
-By default, ikiwiki will do a basic validation and display of the form,
-but if this hook is registered, it will stop that and let the hook take
-over.
+Just before a form is displayed to the user, the `formbuilder` hook is
+called. It can be used to validate the form, but should not display it.
### savestate
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.
+### %pagestate
+
+The `%pagestate` hash can be used by plugins to save state that they will need
+next time ikiwiki is run. The hash holds per-page state, so to set a value,
+use `%pagestate{$page}{$id}{$key}=$value`, and to retrieve the value,
+use `%pagestate{$page}{$id}{$key}`.
+
+`$key` can be any string you like, but `$id` must be the same as the "id"
+parameter passed to `hook()` when registering the plugin. This is so
+ikiwiki can know when to delete pagestate for plugins that are no longer
+used.
+
+When pages are deleted, ikiwiki automatically deletes their pagestate too.
+
+Note that page state does not persist across wiki rebuilds, only across
+wiki updates.
+
### Other variables
If your plugin needs to access data about other pages in the wiki. It can
Given a page name and a destination file name (not including the base
destination directory), register that the page will result in that file
-being rendered. It's important to call this before writing to any file in
-the destination directory.
+being rendered.
+
+It's important to call this before writing to any file in the destination
+directory, and it's important to call it consistently every time, even if
+the file isn't really written this time -- unless you delete any old
+version of the file. In particular, in preview mode, this should still be
+called even if the file isn't going to be written to during the preview.
Ikiwiki uses this information to automatically clean up rendered files when
the page that rendered them goes away or is changes to no longer render
Passed a page and an extension, returns the filename that page will be
rendered to.
+## Internal use pages
+
+Sometimes it's useful to put pages in the wiki without the overhead of
+having them be rendered to individual html files. Such internal use pages
+are collected together to form the RecentChanges page, for example.
+
+To make an internal use page, register a filename extension that starts
+with "_". Internal use pages cannot be edited with the web interface,
+generally shouldn't contain wikilinks or preprocessor directives (use
+either on them with extreme caution), and are not matched by regular
+PageSpecs glob patterns, but instead only by a special `internal()`
+[[ikiwiki/PageSpec]].
+
## RCS plugins
ikiwiki's support for [[revision_control_systems|rcs]] also uses pluggable