X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/63f2eddaa47a53f78dc78ce10f391593759c6d7d..d61935c8ed85e5b4be6292b42516832f42a3a5b0:/doc/plugins/write.mdwn diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn index 8c5c4a04b..889057e69 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 @@ -17,57 +19,416 @@ being edited. ## Registering plugins -Plugins should, when imported, call IkiWiki::register_plugin to hook into -ikiwiki. The function takes four parameters: +All plugins should `use IkiWiki` to import the ikiwiki plugin interface. + +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 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. + +An optional "scan" parameter, if set to a true value, makes the hook be +called during the preliminary scan that ikiwiki makes of updated pages, +before begining to render pages. This parameter should be set to true if +the hook modifies data in `%links`. Note that doing so will make the hook +be run twice per page build, so avoid doing it for expensive hooks. + +An optional "last" parameter, if set to a true value, makes the hook run +after all other hooks of its type. Useful if the hook depends on some other +hook being run first. + +## Types of hooks + +In roughly the order they are called. + +### getopt + + hook(type => "getopt", id => "foo", call => \&getopt); + +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. + +### checkconfig + + 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 +`error()` if something isn't configured right. + +### filter + + 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. -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. +### scan -## Writing a [[PreProcessorDirective]] + hook(type => "scan", id => "foo", call => \&scan); -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. +This is identical to a preprocess hook (see below), except that it is +called in the initial pass that scans pages for data that will be used in +later passes. Scan hooks are the only hook that should modify -## Error handing in plugins +### preprocess -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. +Adding a [[PreProcessorDirective]] is probably the most common use of a +plugin. -## Html issues + hook(type => "preprocess", id => "foo", call => \&preprocess); -Note that if [[HTMLSanitization]] is enabled, html in +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 gives 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 + + 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 + + hook(type => "pagetemplate", id => "foo", call => \&pagetemplate); + +[[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 [[cpan 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 + + 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 + + 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 + + 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 + + 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 + + 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. + +### auth + + hook(type => "auth", id => "foo", call => \&auth); + +This hook can be used to implement a different authentication method than +the standard web form. When a user needs to be authenticated, each registered +auth hook is called in turn, and passed a CGI object and a session object. + +If the hook is able to authenticate the user, it should set the session +object's "name" parameter to the authenticated user's name. Note that +if the name is set to the name of a user who is not registered, +a basic registration of the user will be automatically performed. + +### canedit + + hook(type => "canedit", id => "foo", call => \&pagelocked); + +This hook can be used to implement arbitrary access methods to control when +a page can be edited using the web interface (commits from revision control +bypass it). When a page is edited, each registered canedit hook is called +in turn, and passed the page name, a CGI object, and a session object. + +If edit can proceed, the hook should return "". If the edit is not allowed +by this hook, the hook should return an error message for the user to see. +If the hook has no opinion about whether the edit can proceed, return +`undef`, and the next plugin will be asked to decide. + +### formbuilder + + hook(type => "formbuilder_setup", id => "foo", call => \&formbuilder_setup); + hook(type => "formbuilder", id => "foo", call => \&formbuilder); + +These hooks allow tapping into the parts of ikiwiki that use [[cpan +CGI::FormBuilder]] to generate web forms. These hooks are passed named +parameters: `cgi`, `session`, and `form`. These are, respectively, the +`CGI` object, the user's `CGI::Session`, and a `CGI::FormBuilder`. + +Each time a form is set up, the formbuilder_setup hook is called. +Typically the formbuilder_setup hook will check the form's title, and if +it's a form that it needs to modify, will call various methods to +add/remove/change fields, tweak the validation code for the fields, etc. It +will not validate or display the form. + +Form validation and display can be overridden by the formbuilder hook. +By default, ikiwiki will do a basic validation and display of the form, +but if this hook is registered, it will stop that and let the hook take +over. This hook is passed an additional named parameter: `buttons` is an +array of the submit buttons for the form. + +### 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: -## Wiki configuration + use IkiWiki '1.00'; -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 +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 is linked to from that page 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. +* `%links` lists the names of each page that a page links to, in an array + reference. +* `%renderedfiles` lists names of the files rendered by a page, in an array + reference. +* `%pagesources` contains the name of the source file for a page. + +Also, the %IkiWiki::version variable contains the version number for the +ikiwiki program. + +### Library functions + +#### `hook(@)` + +Hook into ikiwiki's processing. See the discussion of hooks above. + +Note that in addition to the named parameters described above, a parameter +named no_override is supported, If it's set to a true value, then this hook +will not override any existing hook with the same id. This is useful if +the id can be controled by the user. + +#### `debug($)` + +Logs a debugging message. These are supressed unless verbose mode is turned +on. + +#### `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 +cleanup. + +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($;@)` + +Creates and returns a [[cpan HTML::Template]] object. The first parameter +is the name of the file in the template directory. The optional remaining +parameters are passed to HTML::Template->new. + +#### `htmlpage($)` + +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, a [[PageSpec]], and the location the [[PageSpec]] should +be matched against, returns true if the [[PageSpec]] matches the page. (If +the third parameter is not passed, relative PageSpecs will match relative to +the top of the wiki.) + +#### `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 `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. + +After the three required parameters, named parameters can be used to +control some options. These are: + +* noimageinline - set to true to avoid turning links into inline html images +* forcesubpage - set to force a link to a subpage +* linktext - set to force the link text to something +* anchor - set to make the link include an anchor + +#### `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 fourth parameter, if set to a true value, makes the file be +written in binary mode. + +The optional fifth parameter can be used to pass a function reference that +will be called to handle writing to the file. The function will be called +and passed a file descriptor it should write to, and an error recovery +function it should call if the writing fails. (You will not normally need to +use this interface.) + +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. + +### `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 +being rendered. It's important to call this before writing to any file in +the destination directory. + +#### `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. + +#### `gettext` + +This is the standard gettext function, although slightly optimised. + +## 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. + +## PageSpec plugins + +It's also possible to write plugins that add new functions to +[[PageSpecs|PageSpec]]. Such a plugin should add a function to the +IkiWiki::PageSpec package, that is named `match_foo`, where "foo()" is +how it will be accessed in a [[PageSpec]]. The function will be passed two +parameters: The name of the page being matched, and the thing to match +against. It should return true if the page matches.