X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/63f2eddaa47a53f78dc78ce10f391593759c6d7d..aa2b3b8f637d0f3abe2ebf3845a22781ffd83c72:/doc/plugins/write.mdwn

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 8c5c4a04b..dd0ab451f 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -4,7 +4,9 @@ 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
+[[toc levels=2]]
+
+## Considerations
 
 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
@@ -17,39 +19,165 @@ being edited.
 
 ## 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.
+## Types of hooks
 
-## Writing a [[PreProcessorDirective]]
+In roughly the order they are called.
 
-For preprocessor directives, the subroutine 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 subroutine returns goes onto the
-page in place of the directive.
+### getopt
 
-## Error handing in plugins
+	IkiWiki::hook(type => "getopt", id => "foo", call => \&getopt);
 
-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.
+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
 
-## Html issues
+	IkiWiki::hook(type => "filter", id => "foo", call => \&filter);
 
-Note that if [[HTMLSanitization]] is enabled, html in 
+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.
+
+### preprocess
+
+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.
+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.
+
+### 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.
+
+The function is passed named parameters: "page" and "content" and should
+return the htmlized content.
+
+### 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.
+
+### sanitize
+
+	IkiWiki::hook(type => "sanitize", id => "foo", call => \&sanitize);
+
+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.
+
+### format
+
+	IkiWiki::hook(type => "format", id => "foo", call => \&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.
+
+The function is passed named parameters: "page" and "content", and 
+should return the formatted content.
+
+### delete
+
+	IkiWiki::hook(type => "delete", id => "foo", call => \&delete);
+
+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.
+
+### 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
+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
@@ -58,16 +186,47 @@ 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.
-* `%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.
+
+## 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.