X-Git-Url: https://sipb.mit.edu/gitweb.cgi/ikiwiki.git/blobdiff_plain/51d20d72f63b6f633747421c7afde171e189f50d..0f25ec8eb640a850a8f1efe7081c03d05d04eda4:/doc/plugins/write.mdwn?ds=sidebyside

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 90ffca3f4..57521687e 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
@@ -15,178 +17,303 @@ 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
+
+All plugins should `use IkiWiki` to import the ikiwiki plugin interface.
 
-Plugins should, when imported, call IkiWiki::hook to hook into ikiwiki's
+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 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
+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 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.
+	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, 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.
+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 %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.
+	hook(type => "checkconfig", id => "foo", call => \&checkconfig);
 
-## Html issues
+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
+`error()` if something isn't configured right.
 
-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 (or whatever engine is used to htmlize the page) along
-with the rest of the page.
+### filter
 
-# Other types of hooks
+	hook(type => "filter", id => "foo", call => \&filter);
 
-Beyond PreProcessorDirectives, Other types of hooks that can be used by
-plugins include:
+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.
 
-## checkconfig
+### preprocess
 
-	IkiWiki::hook(type => "checkconfig", id => "foo", call => \&checkconfig);
+Adding a [[PreProcessorDirective]] is probably the most common use of a
+plugin.
 
-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.
+        hook(type => "preprocess", id => "foo", call => \&preprocess);
 
-## filter
+Replace "foo" with the command name that will be used inside brackets for
+the preprocessor directive.
 
-	IkiWiki::hook(type => "filter", id => "foo", call => \&filter);
+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.
 
-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.
+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.
 
-## htmlize
+### htmlize
 
-	IkiWiki::hook(type => "htmlize", id => "ext", call => \&filter);
+	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.
 
-## pagetemplate
+The function is passed named parameters: "page" and "content" and should
+return the htmlized content.
+
+### pagetemplate
 
-	IkiWiki::hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
+	hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
 
-Each time a page is rendered, a [[template|templates]] is filled out.
-This hook allows modifying that template. The function is passed named
+[[Templates]] 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 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 `HTML::Template` object that
-is the template that will be used to generate the page. The function 
-can manipulate that template object.
+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. Note that in order to be robust,
-it's a good idea to check whether the template has a variable before trying
-to set it, as setting a variable that's not present is an error.
+a new custom parameter to the template.
 
-	if ($template->query(name => 'foo')) {
-		$template->param("foo" => "bar");
-	}
+### sanitize
 
-## sanitize
-
-	IkiWiki::hook(type => "sanitize", id => "foo", call => \&sanitize);
+	hook(type => "sanitize", id => "foo", call => \&sanitize);
 
 Use this to implement html sanitization or anything else that needs to
-modify the content of a page after it has been fully converted to html.
-The function is passed the page content and should return the sanitized
-content.
+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
+
+	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.
 
-## delete
+The function is passed named parameters: "page" and "content", and 
+should return the formatted content.
 
-	IkiWiki::hook(type => "delete", id => "foo", call => \&dele);
+### delete
+
+	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
+### change
 
-	IkiWiki::hook(type => "change", id => "foo", call => \&render);
+	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
+### cgi
 
-	IkiWiki::hook(type => "cgi", id => "foo", call => \&cgi);
+	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.
 
-# Wiki configuration
+### savestate
+
+	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.
+
+## Plugin interface
+
+To import the ikiwiki plugin interface:
 
-A plugin can access the wiki's configuration via the `%IkiWiki::config`
+	use IkiWiki '1.00';
+
+This will import several variables and functions into your plugin's
+namespace. These variables and functions are the ones most plugins need,
+and a special effort will be made to avoid changing them in incompatible
+ways, and to document any changes that have to be made in the future.
+
+Note that IkiWiki also provides other variables functions that are not
+exported by default. No guarantee is made about these in the future, so if
+it's not exported, the wise choice is to not use it.
+
+### %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
 [[ikiwiki.setup]], which sets the hash content to configure the wiki.
 
-# Wiki data
+### Other variables
 
 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 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::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
-  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.
-
-# A note on generating html links
+* `%links` lists the names of each page that a page links to, in an array
+  reference.
+* `%renderedfiles` contains the name of the file rendered by a page.
+* `%pagesources` contains the name of the source file for a page.
+
+### Library functions
+
+#### `hook(@)`
+
+Hook into ikiwiki's processing. See the discussion of hooks above.
+
+#### `debug($)`
+
+Logs a debugging message. These are supressed unless verbose mode is turned
+on.
+
+#### `error($)`
+
+Aborts with an error message.
+
+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().
+
+#### `template($;@)`
+
+Creates and returns a HTML::Template object. The first parameter is the
+name of the file in the template directory. The optional remaining
+parameters are passed to HTML::Template->new.
+
+#### `htmlpage($)`
+
+Passed a page name, returns the base name that will be used for a the html
+page created from it. (Ie, it appends ".html".)
+
+#### `add_depends($$)`
+
+Makes the specified page depend on the specified [[PageSpec]].
+
+#### `pagespec_match($$)`
+
+Passed a page name, and a [[PageSpec]], returns true if the [[PageSpec]]
+matches the page.
+
+#### `bestlink($$)`
+
+Given a page and the text of a link on the page, determine which
+existing page that link best points to. Prefers pages under a
+subdirectory with the same name as the source page, failing that
+goes down the directory tree to the base looking for matching
+pages, as described in [[SubPage/LinkingRules]].
+
+#### `htmllink($$$;$$$)`
 
 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:
+done by using the `htmllink` function. The usual way to call
+`htmlllink` is:
 
 	htmllink($page, $page, $link)
 
-Why is $page repeated? Because if a page is inlined inside another, and a
+Why is `$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 $destpage is the inlining page. A destpage parameter is passed to some
-of the hook functions above; the ones that are not passed it are not used
+Here `$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
+The remaining three optional parameters to `htmllink` are:
+
+1. noimageinline - set to true to avoid turning links into inline html images
+1. forcesubpage  - set to force a link to a subpage
+1. linktext - set to force the link text to something
+
+#### `readfile($;$)`
+
+Given a filename, reads and returns the entire file.
+
+The optional second parameter, if set to a true value, makes the file be read
+in binary mode.
+
+A failure to read the file will result in it dying with an error.
+
+#### `writefile($$$;$)`
+
+Given a filename, a directory to put it in, and the file's content,
+writes a file. 
+
+The optional second parameter, if set to a true value, makes the file be
+written in binary mode.
+
+A failure to write the file will result in it dying with an error.
+
+If the destination directory doesn't exist, it will first be created.
+
+#### `pagetype($)`
+
+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($)`
+
+Given the name of a source file, returns the name of the wiki page
+that corresponds to that file.
+
+#### `srcfile($)`
+
+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.
+
+#### `displaytime($)`
+
+Given a time, formats it for display.
+
+## RCS plugins
 
 ikiwiki's support for revision control systems also uses pluggable perl
 modules. These are in the `IkiWiki::RCS` namespace, for example