X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/b0952742b29373bd762cf13c258cfd4559a680ad..63c79e7f5b87003cd02158b4d9f723b4c054cacf:/doc/plugins/write.mdwn?ds=sidebyside

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index a4e800c58..583ca541f 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -4,7 +4,7 @@ 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
+# 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
@@ -15,74 +15,165 @@ 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
+# 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.
+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]]
+# Types of hooks
 
-This is probably the most common use of a plugin.
+In roughly the order they are called.
 
-        IkiWiki::hook(type => "preprocess", id => "foo", call => \&preprocess);
+## getopt
 
-Replace "foo" with the command name that will be used inside brackers for the preprocessor directive.
+	IkiWiki::hook(type => "getopt", id => "foo", call => \&getopt);
 
-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.
+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.
 
-### Error handing
+## checkconfig
 
-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.
+	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.
 
-### Html issues
+## preprocess
 
-Note that if [[HTMLSanitization]] is enabled, html in 
+Adding a [[PreProcessorDirective]] 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 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 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.
+
+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 along with the rest of the page.
+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.
+
+## htmlize
+
+	IkiWiki::hook(type => "htmlize", id => "ext", call => \&htmlize);
+
+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.
 
-## Other types of hooks
+## pagetemplate
 
-Beyond PreProcessorDirectives, Other types of hooks that can be used by plugins include:
+	IkiWiki::hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
 
-### checkconfig
+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.
 
-        IkiWiki::hook(type => "checkconfig", id => "foo", call => \&checkconfig);
+The most common thing to do is probably to call $template->param() to add
+a new custom parameter to the template.
 
-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.
+## sanitize
 
-### delete
+	IkiWiki::hook(type => "sanitize", id => "foo", call => \&sanitize);
 
-        IkiWiki::hook(type => "delete", id => "foo", call => \&dele);
+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 the page content and should return the sanitized
+content.
 
-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.
+## format
 
-### render
+	IkiWiki::hook(type => "format", id => "foo", call => \&format);
 
-        IkiWiki::hook(type => "render", id => "foo", call => \&render);
+The function is passed the complete page content and can reformat it
+and return the new content. 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.
 
-Each time ikiwiki renders a change or addition (but not deletion) of a page to the wiki, the referenced function is called, and passed the name of the source file that was rendered.
+## delete
 
-### cgi
+	IkiWiki::hook(type => "delete", id => "foo", call => \&delete);
 
-        IkiWiki::hook(type => "cgi", id => "foo", call => \&cgi);
+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.
 
-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.
+## change
 
-## Wiki configuration
+	IkiWiki::hook(type => "change", id => "foo", call => \&render);
 
-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
+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.
+
+## savestate
+
+	IkiWiki::hook(type => "savestate", id => "foo", call => \&savestate);
+
+This hook is called wheneven ikiwiki normally saves its state, just before
+the state is saved. The function can save other state, modify values before
+they're saved, etc.
+
+## 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.
+
+# 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:
@@ -94,24 +185,34 @@ use the following hashes, using a page name as the key:
 * `%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
+* `%IkiWiki::depends` contains a [[PageSpec]] 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.
+  parameters the page name and a [[PageSpec]] of dependencies to add.
+* `%IkiWiki::forcerebuild` any pages set as the keys to this hash will be
+  treated as if they're modified and rebuilt.
+
+# A note on generating html links
 
-## Page templates
+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:
 
-Plugins are mostly limited to changing the content of pages, to change the look and feel of the wiki it's generally better to use a stylesheet and [[templates]]. However, there are some hooks in the templates that plugins can use to add stuff to the wiki's UI:
+	htmllink($page, $page, $link)
 
-### Adding content to the page header
+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:
 
-Html that is added to $IkiWiki::config{headercontent} will show up in the
-header of the page. One good thing to put here is a search form.
+	htmllink($page, $destpage, $link)
 
-## RCS plugins
+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
@@ -120,3 +221,5 @@ modules. These are in the `IkiWiki::RCS` namespace, for example
 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.