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]].
+[[!template id="note" text="""
+Ikiwiki is a compiler
+
+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.
+
+The [[tutorial]] has some other examples of ways that ikiwiki being a
+compiler may trip up the unwary.
+"""]]
+
[[!toc levels=2]]
+## Highlevel view of ikiwiki
+
+Ikiwiki mostly has two modes of operation. It can either be running
+as a compiler, building or updating a wiki; or as a cgi program, providing
+user interface for editing pages, etc. Almost everything ikiwiki does
+is accomplished by calling various hooks provided by plugins.
+
+### compiler
+
+As a compiler, ikiwiki starts by calling the `refresh` hook. Then it checks
+the wiki's source to find new or changed pages. The `needsbuild` hook is
+then called to allow manipulation of the list of pages that need to be
+built.
+
+Now that it knows what pages it needs to build, ikiwiki runs two
+compile passes. First, it runs `scan` hooks, which collect metadata about
+the pages. Then it runs a page rendering pipeline, by calling in turn these
+hooks: `filter`, `preprocess`, `linkify`, `htmlize`, `postscan`,
+`pagetemplate`, `sanitize`, `format`.
+
+After all necessary pages are built, it calls the `change` hook. Finally,
+if a page is was deleted, the `delete` hook is called, and the files that
+page had previously produced are removed.
+
+### cgi
+
+The flow between hooks when ikiwiki is run as a cgi is best illustrated by
+an example.
+
+Alice browses to a page and clicks Edit.
+
+* Ikiwiki is run as a cgi. It assigns Alice a session cookie, and,
+ by calling the `auth` hooks, sees that she is not yet logged in.
+* The `sessioncgi` hooks are then called, and one of them,
+ from the [[editpage]] plugin, notices that the cgi has been told "do=edit".
+* The [[editpage]] plugin calls the `canedit` hook to check if this
+ page edit is allowed. The [[signinedit]] plugin has a hook that says not:
+ Alice is not signed in.
+* The [[signinedit]] plugin then launches the signin process. A signin
+ page is built by calling the `formbuilder_setup` hook.
+
+Alice signs in with her openid.
+
+* The [[openid]] plugin's `formbuilder` hook sees that an openid was
+ entered in the signin form, and redirects to Alice's openid provider.
+* Alice's openid provider calls back to ikiwiki. The [[openid]] plugin
+ has an `auth` hook that finishes the openid signin process.
+* Signin complete, ikiwiki returns to what Alice was doing before; editing
+ a page.
+* Now all the `canedit` hooks are happy. The [[editpage]] plugin calls
+ `formbuilder_setup` to display the page editing form.
+
+Alice saves her change to the page.
+
+* The [[editpage]] plugin's `formbuilder` hook sees that the Save button
+ was pressed, and calls the `checkcontent` and `editcontent` hooks.
+ Then it saves the page to disk, and branches into the compiler part
+ of ikiwiki to refresh the wiki.
+
## Types of plugins
Most ikiwiki [[plugins]] are written in perl, like ikiwiki. This gives the
explain how to write both sorts of plugins, albeit with an emphasis on perl
plugins.
-## Remember: Ikiwiki is a compiler
-
-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. The [[tutorial]] has some other examples of ways that ikiwiki
-being a compiler may trip up the unwary.
-
## Plugin interface
To import the ikiwiki plugin interface:
describing the option. There can also be an item named "plugin", which
describes the plugin as a whole. For example:
- return
+ return
plugin => {
description => "description of this plugin",
safe => 1,
This hook is used to inject C code (which it returns) into the `main`
function of the ikiwiki wrapper when it is being generated.
-### Exported variables
+## Exported variables
Several variables are exported to your plugin when you `use IkiWiki;`
-#### %config
+### `%config`
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
your ikiwiki setup file, which sets the hash content to configure the wiki.
-#### %pagestate
+### `%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,
Note that page state does not persist across wiki rebuilds, only across
wiki updates.
-#### %wikistate
+### `%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
"id" parameter passed to `hook()` when registering the plugin, so that the
state can be dropped if the plugin is no longer used.
-#### %links
+### `%links`
The `%links` hash can be used to look up the names of each page that
a page links to. The name of the page is the key; the value is an array
reference. Do not modify this hash directly; call `add_link()`.
-#### %destsources
+ $links{"foo"} = ["bar", "baz"];
+
+### `%pagesources`
+
+The `%pagesources` has can be used to look up the source filename
+of a page. So the key is the page name, and the value is the source
+filename. Do not modify this hash.
+
+ $pagesources{"foo"} = "foo.mdwn";
+
+### `%destsources`
The `%destsources` hash records the name of the source file used to
create each destination file. The key is the output filename (ie,
"foo/index.html"), and the value is the source filename that it was built
from (eg, "foo.mdwn"). Note that a single source file may create multiple
destination files. Do not modify this hash directly; call `will_render()`.
+
+ $destsources{"foo/index.html"} = "foo.mdwn";
-#### %pagesources
-
-The `%pagesources` has can be used to look up the source filename
-of a page. So the key is the page name, and the value is the source
-filename. Do not modify this hash.
+## Library functions
-### Library functions
+Several functions are exported to your plugin when you `use IkiWiki;`
-#### `hook(@)`
+### `hook(@)`
Hook into ikiwiki's processing. See the discussion of hooks above.
will not override any existing hook with the same id. This is useful if
the id can be controled by the user.
-#### `debug($)`
+### `debug($)`
Logs a debugging message. These are supressed unless verbose mode is turned
on.
-#### `error($;$)`
+### `error($;$)`
Aborts with an error message. If the second parameter is passed, it is a
function that is called after the error message is printed, to do any final
dying on bad input when building a page, as that will halt
the entire wiki build and make the wiki unusable.
-#### `template($;@)`
+### `template($;@)`
Creates and returns a [[!cpan HTML::Template]] object. The first parameter
is the name of the file in the template directory. The optional remaining
parameters are passed to `HTML::Template->new`.
-#### `htmlpage($)`
+### `htmlpage($)`
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.
-#### `pagespec_match_list($$;@)`
+### `pagespec_match_list($$;@)`
Passed a page name, and [[ikiwiki/PageSpec]], returns a list of pages
in the wiki that match the [[ikiwiki/PageSpec]].
Any other named parameters are passed on to `pagespec_match`, to further
limit the match.
-#### `add_depends($$;$)`
+### `add_depends($$;$)`
Makes the specified page depend on the specified [[ikiwiki/PageSpec]].
page will be updated whenever anything matching the PageSpec is modified.
This can be overridden by passing a `deptype` value as the third parameter.
-#### `pagespec_match($$;@)`
+### `pagespec_match($$;@)`
Passed a page name, and [[ikiwiki/PageSpec]], returns a true value if the
[[ikiwiki/PageSpec]] matches the page.
PageSpec should match against. If not passed, relative PageSpecs will match
relative to the top of the wiki.
-#### `deptype(@)`
+### `deptype(@)`
Use this function to generate ikiwiki's internal representation of a
dependency type from one or more of these keywords:
If multiple types are specified, they are combined.
-#### `bestlink($$)`
+### `bestlink($$)`
Given a page and the text of a link on the page, determine which
existing page that link best points to. Prefers pages under a
goes down the directory tree to the base looking for matching
pages, as described in [[ikiwiki/SubPage/LinkingRules]].
-#### `htmllink($$$;@)`
+### `htmllink($$$;@)`
Many plugins need to generate html links and add them to a page. This is
done by using the `htmllink` function. The usual way to call
* class - set to add a css class to the link
* title - set to add a title attribute to the link
-#### `readfile($;$)`
+### `readfile($;$)`
Given a filename, reads and returns the entire file.
A failure to read the file will result in it dying with an error.
-#### `writefile($$$;$$)`
+### `writefile($$$;$$)`
Given a filename, a directory to put it in, and the file's content,
writes a file.
the srcdir or destdir, and any subdirectories of this are included in the
filename parameter.
-#### `will_render($$)`
+### `will_render($$)`
Given a page name and a destination file name (not including the base
destination directory), register that the page will result in that file
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($)`
+### `pagetype($)`
Given the name of a source file, returns the type of page it is, if it's
a type that ikiwiki knowns how to htmlize. Otherwise, returns undef.
-#### `pagename($)`
+### `pagename($)`
Given the name of a source file, returns the name of the wiki page
that corresponds to that file.
-#### `pagetitle($)`
+### `pagetitle($)`
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($)`
+### `titlepage($)`
This performs the inverse of `pagetitle`, ie, it converts a page title into
a wiki page name.
-#### `linkpage($)`
+### `linkpage($)`
This converts text that could have been entered by the user as a
[[ikiwiki/WikiLink]] into a wiki page name.
-#### `srcfile($;$)`
+### `srcfile($;$)`
Given the name of a source file in the wiki, searches for the file in
the source directory and the underlay directories (most recently added
be found. The second parameter can be set to a true value to make it return
undef instead.
-#### `add_underlay($)`
+### `add_underlay($)`
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($;$)`
+### `displaytime($;$)`
Given a time, formats it for display.
The optional second parameter is a strftime format to use to format the
time.
-#### `gettext`
+### `gettext`
This is the standard gettext function, although slightly optimised.
-#### `urlto($$;$)`
+### `ngettext`
+
+This is the standard ngettext function, although slightly optimised.
+
+### `urlto($$;$)`
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
If the third parameter is passed and is true, an absolute url will be
constructed instead of the default relative url.
-#### `newpagefile($$)`
+### `newpagefile($$)`
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($$;$)`
+### `targetpage($$;$)`
Passed a page and an extension, returns the filename that page will be
rendered to.
filename of the page. For example, `targetpage("foo", "rss", "feed")`
will yield something like `foo/feed.rss`.
-#### `add_link($$)`
+### `add_link($$)`
This adds a link to `%links`, ensuring that duplicate links are not
added. Pass it the page that contains the link, and the link text.