it's not really hard. This page is a complete reference to everything a
plugin might want to do. There is also a quick [[tutorial]].
-[[toc levels=2]]
+[[!toc levels=2]]
## Types of plugins
Plugins should, when imported, call `hook()` to hook into ikiwiki's
processing. The function uses named parameters, and use varies depending on
-the type of hook being registered -- see below. Note that a plugin can call
-the function more than once to register multiple hooks. All calls to
-`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 tells what function to call for the hook.
+the type of hook being registered -- see below. A plugin can call
+the function more than once to register multiple hooks.
+
+All calls to `hook()` should be passed a "type" parameter, which gives the
+type of hook, a "id" parameter, which should be a unique string for this
+plugin, and a "call" parameter, which tells what function to call for the
+hook.
An optional "last" parameter, if set to a true value, makes the hook run
after all other hooks of its type. Useful if the hook depends on some other
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.
+### scan
+
+ hook(type => "scan", id => "foo", call => \&scan);
+
+This hook is called early in the process of building the wiki, and is used
+as a first pass scan of the page, to collect metadata about the page. It's
+mostly used to scan the page for WikiLinks, and add them to `%links`.
+Present in IkiWiki 2.40 and later.
+
+The function is passed named parameters "page" and "content". Its return
+value is ignored.
+
### filter
hook(type => "filter", id => "foo", call => \&filter);
### preprocess
-Adding a [[PreProcessorDirective]] is probably the most common use of a
-plugin.
+Adding a preprocessor [[ikiwiki/directive]] is probably the most common use
+of a plugin.
hook(type => "preprocess", id => "foo", call => \&preprocess);
-Replace "foo" with the command name that will be used inside brackets 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 gives the name of the page the
-content is going to (different for inlined pages), and a "preview"
-parameter is set to a true value if the page is being previewed. 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
+Replace "foo" with the command name that will be used for the preprocessor
directive.
-An optional "scan" parameter, if set to a true value, makes the hook be
-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.
+Each time the directive is processed, the referenced function (`preprocess`
+in the example above) is called. Whatever the function returns goes onto
+the page in place of the directive. Or, if the function aborts using
+`error()`, the directive will be replaced with the error message.
+
+The function is passed named parameters. First come the parameters set
+in the preprocessor directive. These are passed in the same order as
+they're in the directive, and if the preprocessor directive contains a bare
+parameter (example: `\[[!foo param]]`), that parameter will be passed with
+an empty value.
+
+After the parameters from the preprocessor directive some additional ones
+are passed: A "page" parameter gives the name of the page that embedded the
+preprocessor directive, while a "destpage" parameter gives the name of the
+page the content is going to (different for inlined pages), and a "preview"
+parameter is set to a true value if the page is being previewed.
+
+If `hook` is passed an optional "scan" parameter, set to a true value, this
+makes the hook be called during the preliminary scan that ikiwiki makes of
+updated pages, before begining to render pages. This should be done 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. (As an
+optimisation, if your preprocessor hook is called in a void context, you
+can assume it's being run in scan mode, and avoid doing expensive things at
+that point.)
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
-linkified and passed through markdown (or whatever engine is used to htmlize
-the page) along with the rest of the page.
+preprocessor [[ikiwiki/directive]] 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 linkified and passed through markdown (or whatever engine is used to
+htmlize the page) along with the rest of the page.
+
+### linkify
+
+ hook(type => "linkify", id => "foo", call => \&linkify);
+
+This hook is called to convert [[WikiLinks|WikiLink]] on the page into html
+links. The function is passed named parameters "page", "destpage", and
+"content". It should return the linkified content. Present in IkiWiki 2.40
+and later.
+
+Plugins that implement linkify must also implement a scan hook, that scans
+for the links on the page and adds them to `%links`.
### htmlize
hook(type => "htmlize", id => "ext", call => \&htmlize);
-Runs on the raw source of a page and turns it into html. The id parameter
+Runs on the 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.
The function is passed named parameters: "page" and "content" and should
return the htmlized content.
+If `hook` is passed an optional "keepextension" parameter, set to a true
+value, then this extension will not be stripped from the source filename when
+generating the page.
+
### pagetemplate
hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
-[[Templates|wikitemplate]] are filled out for many different things in
+[[Templates|wikitemplates]] are filled out for many different things in
ikiwiki, like generating a page, or part of a blog page, or an rss feed, or
a cgi. This hook allows modifying the variables available on those
templates. The function is passed named parameters. The "page" and
"destpage" parameters are the same as for a preprocess hook. The "template"
-parameter is a [[cpan HTML::Template]] object that is the template that
+parameter is a [[!cpan HTML::Template]] object that is the template that
will be used to generate the page. The function can manipulate that
template object.
hook(type => "templatefile", id => "foo", call => \&templatefile);
-This hook allows plugins to change the [[template|wikitemplate]] that is
+This hook allows plugins to change the [[template|wikitemplates]] that is
used for a page in the wiki. The hook is passed a "page" parameter, and
should return the name of the template file to use, or undef if it doesn't
want to change the default ("page.tmpl"). Template files are looked for in
Use this to implement html sanitization or anything else that needs to
modify the body of a page after it has been fully converted to html.
-The function is passed named parameters: "page" and "content", and
-should return the sanitized content.
+The function is passed named parameters: "page", "destpage", and "content",
+and should return the sanitized content.
+
+### postscan
+
+ hook(type => "postscan", id => "foo", call => \&postscan);
+
+This hook is called once the full page body is available (but before the
+format hook). The most common use is to update search indexes. Added in
+ikiwiki 2.54.
+
+The function is passed named parameters "page" and "content". Its return
+value is ignored.
### format
The difference between format and sanitize is that sanitize only acts on
the page body, while format can modify the entire html page including the
-header and footer inserted by ikiwiki, the html document type, etc.
+header and footer inserted by ikiwiki, the html document type, etc. (It
+should not rely on always being passed the entire page, as it won't be
+when the page is being previewed.)
The function is passed named parameters: "page" and "content", and
should return the formatted content.
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
hook(type => "auth", id => "foo", call => \&auth);
-This hook can be used to implement a different authentication method than
-the standard web form. When a user needs to be authenticated, each registered
-auth hook is called in turn, and passed a CGI object and a session object.
+This hook can be used to implement an authentication method. When a user
+needs to be authenticated, each registered auth hook is called in turn, and
+passed a CGI object and a session object.
If the hook is able to authenticate the user, it should set the session
object's "name" parameter to the authenticated user's name. Note that
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
+
+ hook(type => "editcontent", id => "foo", call => \&editcontent);
+
+This hook is called when a page is saved (or previewed) using the web
+interface. It is passed named parameters: `content`, `page`, `cgi`, and
+`session`. These are, respectively, the new page content as entered by the
+user, the page name, a `CGI` object, and the user's `CGI::Session`.
+
+It can modify the content as desired, and should return the content.
### formbuilder
hook(type => "formbuilder_setup", id => "foo", call => \&formbuilder_setup);
hook(type => "formbuilder", id => "foo", call => \&formbuilder);
-These hooks allow tapping into the parts of ikiwiki that use [[cpan
+These hooks allow tapping into the parts of ikiwiki that use [[!cpan
CGI::FormBuilder]] to generate web forms. These hooks are passed named
parameters: `cgi`, `session`, `form`, and `buttons`. These are, respectively,
the `CGI` object, the user's `CGI::Session`, a `CGI::FormBuilder`, and a
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
hook(type => "savestate", id => "foo", call => \&savestate);
-This hook is called wheneven ikiwiki normally saves its state, just before
+This hook is called whenever ikiwiki normally saves its state, just before
the state is saved. The function can save other state, modify values before
they're saved, etc.
+### displaytime
+
+ hook(type => "displaytime", id => "foo", call => \&display);
+
+This hook can be registered to override the regular `displaytime` function.
+Only the last displaytime hook will be used.
+
+### renamepage
+
+ hook(type => "renamepage", id => "foo", call => \&renamepage);
+
+This hook is called by the [[plugins/rename]] plugin when it renames
+something. The hook is passed named parameters: `page`, `oldpage`,
+`newpage`, and `content`, and should try to modify the content to reflect
+the name change. For example, by converting links to point to the new page.
+
+### getsetup
+
+ hook(type => "getsetup", id => "foo", call => \&getsetup);
+
+This hooks is not called during normal operation, but only when setting up
+the wiki, or generating a setup file. Plugins can use this hook to add
+configuration options.
+
+The hook is passed no parameters. It returns data about the configuration
+options added by the plugin. It can also check if the plugin is usable, and
+die if not, which will cause the plugin to not be offered in the configuration
+interface.
+
+The data returned is a list of `%config` options, followed by a hash
+describing the option. There can also be an item named "plugin", which
+describes the plugin as a whole. For example:
+
+ return
+ option_foo => {
+ type => "boolean",
+ description => "enable foo?",
+ advanced => 1,
+ safe => 1,
+ rebuild => 1,
+ },
+ option_bar => {
+ type => "string",
+ example => "hello",
+ description => "option bar",
+ safe => 1,
+ rebuild => 0,
+ },
+ plugin => {
+ description => "description of this plugin",
+ safe => 1,
+ rebuild => 1,
+ },
+
+* `type` can be "boolean", "string", "integer", "pagespec",
+ or "internal" (used for values that are not user-visible). The type is
+ the type of the leaf values; the `%config` option may be an array or
+ hash of these.
+* `example` can be set to an example value.
+* `description` is a short description of the option.
+* `link` is a link to further information about the option. This can either
+ be a wikilink, or an url.
+* `advanced` can be set to true if the option is more suitable for advanced
+ users.
+* `safe` should be false if the option should not be displayed in unsafe
+ configuration methods, such as the web interface. Anything that specifies
+ a command to run, a path on disk, or a regexp should be marked as unsafe.
+ If a plugin is marked as unsafe, that prevents it from being
+ enabled/disabled.
+* `rebuild` should be true if changing the option (or enabling/disabling
+ the plugin) will require a wiki rebuild, false if no rebuild is needed,
+ and undef if a rebuild could be needed in some circumstances, but is not
+ strictly required.
+
## Plugin interface
To import the ikiwiki plugin interface:
- use IkiWiki '1.00';
+ use IkiWiki '2.00';
This will import several variables and functions into your plugin's
namespace. These variables and functions are the ones most plugins need,
A plugin can access the wiki's configuration via the `%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.
+your ikiwiki setup file, 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}{$key}`.
+
+The `$value` can be anything that perl's Storable module is capable of
+serializing. `$key` can be any string you like, but `$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.
+
+### %wikistate
+
+The `%wikistate` hash can be used by a plugin to store persistant state
+that is not bound to any one page. To set a value, use
+`$wikistate{$id}{$key}=$value, where `$value` is anything Storable can
+serialize, `$key` is any string you like, and `$id` must be the same as the
+"id" parameter passed to `hook()` when registering the plugin, so that the
+state can be dropped if the plugin is no longer used.
### Other variables
function that is called after the error message is printed, to do any final
cleanup.
-Note that while any plugin can use this for a fatal error, plugins should
-try to avoid dying on bad input, as that will halt the entire wiki build
-and make the wiki unusable. So for example, if a [[PreProcessorDirective]]
-is passed bad parameters, it's better to return an error message, which can
-appear on the wiki page, rather than calling error().
+If called inside a preprocess hook, error() does not abort the entire
+wiki build, but instead replaces the preprocessor [[ikiwiki/directive]] with
+a version containing the error message.
+
+In other hooks, error() is a fatal error, so use with care. Try to avoid
+dying on bad input when building a page, as that will halt
+the entire wiki build and make the wiki unusable.
#### `template($;@)`
-Creates and returns a [[cpan HTML::Template]] object. The first parameter
+Creates and returns a [[!cpan HTML::Template]] object. The first parameter
is the name of the file in the template directory. The optional remaining
parameters are passed to `HTML::Template->new`.
Passed a page name, returns the base name that will be used for a the html
page created from it. (Ie, it appends ".html".)
+Use this when constructing the filename of a html file. Use `urlto` when
+generating a link to a page.
+
#### `add_depends($$)`
-Makes the specified page depend on the specified [[PageSpec]].
+Makes the specified page depend on the specified [[ikiwiki/PageSpec]].
#### `pagespec_match($$;@)`
-Passed a page name, and [[PageSpec]], returns true if the [[PageSpec]]
-matches the page.
+Passed a page name, and [[ikiwiki/PageSpec]], returns true if the
+[[ikiwiki/PageSpec]] matches the page.
Additional named parameters can be passed, to further limit the match.
The most often used is "location", which specifies the location the
existing page that link best points to. Prefers pages under a
subdirectory with the same name as the source page, failing that
goes down the directory tree to the base looking for matching
-pages, as described in [[SubPage/LinkingRules]].
+pages, as described in [[ikiwiki/SubPage/LinkingRules]].
#### `htmllink($$$;@)`
* forcesubpage - set to force a link to a subpage
* linktext - set to force the link text to something
* anchor - set to make the link include an anchor
-* rel - set to add a rel attribute to the link.
+* rel - set to add a rel attribute to the link
+* class - set to add a css class to the link
#### `readfile($;$)`
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 changed to no longer render
+them. will_render also does a few important security checks.
#### `pagetype($)`
Given the name of a source file, returns the name of the wiki page
that corresponds to that file.
-#### `srcfile($)`
+#### `pagetitle($)`
+
+Give the name of a wiki page, returns a version suitable to be displayed as
+the page's title. This is accomplished by de-escaping escaped characters in
+the page name. "_" is replaced with a space, and '__NN__' is replaced by
+the UTF character with code NN.
+
+#### `titlepage($)`
+
+This performs the inverse of `pagetitle`, ie, it converts a page title into
+a wiki page name.
+
+#### `linkpage($)`
+
+This converts text that could have been entered by the user as a
+[[WikiLink]] into a wiki page name.
+
+#### `srcfile($;$)`
Given the name of a source file in the wiki, searches for the file in
-the source directory and the underlay directory, and returns the full
-path to the first file found.
+the source directory and the underlay directories (most recently added
+underlays first), and returns the full path to the first file found.
+
+Normally srcfile will fail with an error message if the source file cannot
+be found. The second parameter can be set to a true value to make it return
+undef instead.
+
+#### `add_underlay($)`
-#### `displaytime($)`
+Adds a directory to the set of underlay directories that ikiwiki will
+search for files.
+
+If the directory name is not absolute, ikiwiki will assume it is in
+the parent directory of the configured underlaydir.
+
+#### `displaytime($;$)`
Given a time, formats it for display.
+The optional second parameter is a strftime format to use to format the
+time.
+
#### `gettext`
This is the standard gettext function, although slightly optimised.
-#### `urlto($$)`
+#### `urlto($$;$)`
Construct a relative url to the first parameter from the page named by the
second. The first parameter can be either a page name, or some other
destination file, as registered by `will_render`.
+If the third parameter is passed and is true, an absolute url will be
+constructed instead of the default relative url.
+
+#### `newpagefile($$)`
+
+This can be called when creating a new page, to determine what filename
+to save the page to. It's passed a page name, and its type, and returns
+the name of the file to create, relative to the srcdir.
+
#### `targetpage($$)`
Passed a page and an extension, returns the filename that page will be
rendered to.
-## RCS plugins
+## Miscellaneous
+
+### Internal use pages
+
+Sometimes it's useful to put pages in the wiki without the overhead of
+having them be rendered to individual html files. Such internal use pages
+are collected together to form the RecentChanges page, for example.
+
+To make an internal use page, register a filename extension that starts
+with "_". Internal use pages cannot be edited with the web interface,
+generally shouldn't contain wikilinks or preprocessor directives (use
+either on them with extreme caution), and are not matched by regular
+PageSpecs glob patterns, but instead only by a special `internal()`
+[[ikiwiki/PageSpec]].
+
+### RCS plugins
+
+ikiwiki's support for [[revision_control_systems|rcs]] is also done via
+plugins. See [[RCS_details|rcs/details]] for some more info.
+
+RCS plugins must register a number of hooks. Each hook has type 'rcs',
+and the 'id' field is set to the name of the hook. For example:
+
+ hook(type => "rcs", id => "rcs_update", call => \&rcs_update);
+ hook(type => "rcs", id => "rcs_prepedit", call => \&rcs_prepedit);
+
+#### `rcs_update()`
+
+Updates the working directory with any remote changes.
+
+#### `rcs_prepedit($)`
+
+Is passed a file to prepare to edit. It can generate and return an arbitrary
+token, that will be passed into `rcs_commit` when committing. For example,
+it might return the current revision ID of the file, and use that
+information later when merging changes.
+
+#### `rcs_commit($$$;$$)`
+
+Passed a file, message, token (from `rcs_prepedit`), user, and ip address.
+Should try to commit the file. Returns `undef` on *success* and a version
+of the page with the rcs's conflict markers on failure.
+
+#### `rcs_commit_staged($$$)`
+
+Passed a message, user, and ip address. Should commit all staged changes.
+Returns undef on success, and an error message on failure.
+
+Changes can be staged by calls to `rcs_add, `rcs_remove`, and
+`rcs_rename`.
+
+#### `rcs_add($)`
+
+Adds the passed file to the archive. The filename is relative to the root
+of the srcdir.
+
+Note that this should not commit the new file, it should only
+prepare for it to be committed when rcs_commit (or `rcs_commit_staged`) is
+called. Note that the file may be in a new subdir that is not yet in
+to version control; the subdir can be added if so.
+
+#### `rcs_remove($)`
+
+Remove a file. The filename is relative to the root of the srcdir.
+
+Note that this should not commit the removal, it should only prepare for it
+to be committed when `rcs_commit` (or `rcs_commit_staged`) is called. Note
+that the new file may be in a new subdir that is not yet in version
+control; the subdir can be added if so.
+
+#### `rcs_rename($$)`
-ikiwiki's support for revision control systems also uses pluggable perl
-modules. These are in the `IkiWiki::RCS` namespace, for example
-`IkiWiki::RCS::svn`.
+Rename a file. The filenames are relative to the root of the srcdir.
-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.
+Note that this should not commit the rename, it should only
+prepare it for when `rcs_commit` (or `rcs_commit_staged`) is called.
+The new filename may be in a new subdir, that is not yet added to
+version control. If so, the subdir will exist already, and should
+be added to revision control.
-See [[about_RCS_backends]] for some more info.
+#### `rcs_recentchanges($)`
-## PageSpec plugins
+Examine the RCS history and generate a list of recent changes.
+The parameter is how many changes to return.
+
+The data structure returned for each change is:
+
+ {
+ rev => # the RCSs id for this commit
+ user => # name of user who made the change,
+ committype => # either "web" or the name of the rcs,
+ when => # time when the change was made,
+ message => [
+ { line => "commit message line 1" },
+ { line => "commit message line 2" },
+ # etc,
+ ],
+ pages => [
+ {
+ page => # name of page changed,
+ diffurl => # optional url to a diff of changes
+ },
+ # repeat for each page changed in this commit,
+ ],
+ }
+
+#### `rcs_diff($)`
+
+The parameter is the rev from `rcs_recentchanges`.
+Should return a list of lines of the diff (including \n) in list
+context, and the whole diff in scalar context.
+
+#### `rcs_getctime($)`
+
+This is used to get the page creation time for a file from the RCS, by looking
+it up in the history.
+
+It's ok if this is not implemented, and throws an error.
+
+### PageSpec plugins
It's also possible to write plugins that add new functions to
-[[PageSpecs|PageSpec]]. Such a plugin should add a function to the
+[[PageSpecs|ikiwiki/PageSpec]]. Such a plugin should add a function to the
IkiWiki::PageSpec package, that is named `match_foo`, where "foo()" is
-how it will be accessed in a [[PageSpec]]. The function will be passed
+how it will be accessed in a [[ikiwiki/PageSpec]]. The function will be passed
two parameters: The name of the page being matched, and the thing to match
against. It may also be passed additional, named parameters. It should return
a IkiWiki::SuccessReason object if the match succeeds, or an
IkiWiki::FailReason object if the match fails.
+
+### Setup plugins
+
+The ikiwiki setup file is loaded using a pluggable mechanism. If you look
+at the top of a setup file, it starts with 'use IkiWiki::Setup::Standard',
+and the rest of the file is passed to that module's import method.
+
+It's possible to write other modules in the `IkiWiki::Setup::` namespace that
+can be used to configure ikiwiki in different ways. These modules should,
+when imported, populate `$IkiWiki::Setup::raw_setup` with a reference
+to a hash containing all the config items. They should also implement a
+`gendump` function.
+
+By the way, to parse a ikiwiki setup file and populate `%config`, a
+program just needs to do something like:
+`use IkiWiki::Setup; IkiWiki::Setup::load($filename)`
+
+### Javascript
+
+Some plugins use javascript to make ikiwiki look a bit more web-2.0-ish.
+
+All javascript code should be put in `.js` files in the `javascript`
+underlay, and plugins using those files can enable use of the underlay by
+calling `add_underlay("javascript");` in their `import` function.
+
+You'll have to arrange for `<script>` tags to be added to the pages that
+use your javascript. This can be done using a `format` hook.
+
+Ikiwiki provides some utility functions in `ikiwiki.js`, for use by other
+javascript code. These include:
+
+#### `getElementsByClass(cls, node, tag)`
+
+Returns an array of elements with the given class. The node and tag are
+optional and define what document node and element names to search.
+
+#### `hook(name, call)`
+
+The function `call` will be run as part of the hook named `name`.
+
+Note that to hook into `window.onload`, you can use the `onload' hook.
+
+#### `run_hooks(name)`
+
+Runs the hooks with the specified name.