200 lines
7.9 KiB
Markdown
200 lines
7.9 KiB
Markdown
ikiwiki [[plugins]] are written in perl. Each plugin is a perl module, in
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the `IkiWiki::Plugin` namespace. The name of the plugin is typically in
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lowercase, such as `IkiWiki::Plugin::inline`. Ikiwiki includes a
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`IkiWiki::Plugin::skeleton` that can be fleshed out to make a useful
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plugin. `IkiWiki::Plugin::pagecount` is another simple example.
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# Note
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One thing to keep in mind when writing a plugin is that ikiwiki is a wiki
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*compiler*. So plugins influence pages when they are built, not when they
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are loaded. A plugin that inserts the current time into a page, for
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example, will insert the build time. Also, as a compiler, ikiwiki avoids
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rebuilding pages unless they have changed, so a plugin that prints some
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random or changing thing on a page will generate a static page that won't
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change until ikiwiki rebuilds the page for some other reason, like the page
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being edited.
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# Registering plugins
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Plugins should, when imported, call IkiWiki::hook to hook into ikiwiki's
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processing. The function uses named parameters, and use varies depending on
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the type of plugin being registered. Note that a plugin can call the
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function more than once to register multiple hooks. All calls to
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IkiWiki::hook should be passed a "type" parameter, which gives the type of
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hook, a "id" paramter, which should be a unique string for this plugin, and
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a "call" parameter, which is a reference to a function to call for the
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hook.
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# Writing a [[PreProcessorDirective]]
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This is probably the most common use of a plugin.
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IkiWiki::hook(type => "preprocess", id => "foo", call => \&preprocess);
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Replace "foo" with the command name that will be used inside brackers for
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the preprocessor directive.
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Each time the directive is processed, the referenced function (`preprocess`
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in the example above) is called, and is passed named parameters. A "page"
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parameter gives the name of the page that embedded the preprocessor
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directive, while a "destpage" parameter gices the name of the page the
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content is going to (different for inlined pages). All parameters included
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in the directive are included as named parameters as well. Whatever the
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function returns goes onto the page in place of the directive.
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## Error handing
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While a plugin can call ikiwiki's error routine for a fatal error, for
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errors that aren't intended to halt the entire wiki build, including bad
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parameters passed to a [[PreProcessorDirective]], etc, it's better to just
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return the error message as the output of the plugin.
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## Html issues
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Note that if the [[htmlscrubber]] is enabled, html in
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[[PreProcessorDirective]] output is sanitised, which may limit what your
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plugin can do. Also, the rest of the page content is not in html format at
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preprocessor time. Text output by a preprocessor directive will be passed
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through markdown (or whatever engine is used to htmlize the page) along
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with the rest of the page.
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# Other types of hooks
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Beyond PreProcessorDirectives, Other types of hooks that can be used by
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plugins include:
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## checkconfig
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IkiWiki::hook(type => "checkconfig", id => "foo", call => \&checkconfig);
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This is useful if the plugin needs to check for, or modify ikiwiki's
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configuration. It's called early in the ikiwiki startup process. The
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function is passed no values. It's ok for the function to call
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IkiWiki::error if something isn't configured right.
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## filter
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IkiWiki::hook(type => "filter", id => "foo", call => \&filter);
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Runs on the raw source of a page, before anything else touches it, and can
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make arbitrary changes. The function is passed named parameters `page` and
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`content` and should return the filtered content.
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## htmlize
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IkiWiki::hook(type => "htmlize", id => "ext", call => \&filter);
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Runs on the raw source of a page and turns it into html. The id parameter
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specifies the filename extension that a file must have to be htmlized using
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this plugin. This is how you can add support for new and exciting markup
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languages to ikiwiki.
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## pagetemplate
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IkiWiki::hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
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Each time a page is rendered, a [[template|templates]] is filled out.
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This hook allows modifying that template. The function is passed named
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parameters. The "page" and "destpage" parameters are the same as for a
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preprocess hook. The "template" parameter is a `HTML::Template` object that
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is the template that will be used to generate the page. The function
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can manipulate that template object.
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The most common thing to do is probably to call $template->param() to add
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a new custom parameter to the template. Note that in order to be robust,
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it's a good idea to check whether the template has a variable before trying
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to set it, as setting a variable that's not present is an error.
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if ($template->query(name => 'foo')) {
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$template->param("foo" => "bar");
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}
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## sanitize
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IkiWiki::hook(type => "sanitize", id => "foo", call => \&sanitize);
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Use this to implement html sanitization or anything else that needs to
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modify the content of a page after it has been fully converted to html.
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The function is passed the page content and should return the sanitized
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content.
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## delete
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IkiWiki::hook(type => "delete", id => "foo", call => \&dele);
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Each time a page or pages is removed from the wiki, the referenced function
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is called, and passed the names of the source files that were removed.
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## change
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IkiWiki::hook(type => "change", id => "foo", call => \&render);
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Each time ikiwiki renders a change or addition (but not deletion) to the
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wiki, the referenced function is called, and passed the names of the
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source files that were rendered.
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## cgi
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IkiWiki::hook(type => "cgi", id => "foo", call => \&cgi);
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Use this to hook into ikiwiki's cgi script. Each registered cgi hook is
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called in turn, and passed a CGI object. The hook should examine the
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parameters, and if it will handle this CGI request, output a page and
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terminate the program.
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# Wiki configuration
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A plugin can access the wiki's configuration via the `%IkiWiki::config`
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hash. The best way to understand the contents of the hash is to look at
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[[ikiwiki.setup]], which sets the hash content to configure the wiki.
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# Wiki data
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If your plugin needs to access data about other pages in the wiki. It can
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use the following hashes, using a page name as the key:
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* `%IkiWiki::links` lists the names of each page
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that a page links to, in an array reference.
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* `%IkiWiki::pagemtime` contains the last modification time of each page
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* `%IkiWiki::pagectime` contains the creation time of each page
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* `%IkiWiki::renderedfiles` contains the name of the file rendered by a
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page
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* `%IkiWiki::pagesources` contains the name of the source file for a page.
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* `%IkiWiki::depends` contains a [[GlobList]] that is used to specify other
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pages that a page depends on. If one of its dependencies is updated, the
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page will also get rebuilt.
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Many plugins will need to add dependencies to this hash; the best way to do
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it is by using the IkiWiki::add_depends function, which takes as its
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parameters the page name and a [[GlobList]] of dependencies to add.
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# A note on generating html links
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Many plugins need to generate html links and add them to a page. This is
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done by using the `IkiWiki::htmllink` function. The usual way to call
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htmlllink is:
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htmllink($page, $page, $link)
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Why is $page repeated? Because if a page is inlined inside another, and a
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link is placed on it, the right way to make that link is actually:
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htmllink($page, $destpage, $link)
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Here $destpage is the inlining page. A destpage parameter is passed to some
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of the hook functions above; the ones that are not passed it are not used
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during inlining and don't need to worry about this issue.
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# RCS plugins
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ikiwiki's support for revision control systems also uses pluggable perl
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modules. These are in the `IkiWiki::RCS` namespace, for example
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`IkiWiki::RCS::svn`.
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Each RCS plugin must support all the IkiWiki::rcs\_* functions.
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See IkiWiki::RCS::Stub for the full list of functions. It's ok if
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rcs\_getctime does nothing except for throwing an error.
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See [[about_RCS_backends]] for some more info.
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