document that pagestate values can be anything Storable handles

[ikiwiki.git] / doc / plugins / write.mdwn

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 9c3a36b8fb516a72e0b3dbc01ad343348bd4173f..606031cf2b37d53595b4bae5917bd21c120c46e1 100644 (file)
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -142,6 +142,30 @@ 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.
 
+### linkify
+
+       hook(type => "linkify", id => "foo", call => \&linkify);
+
+This hook is called to convert [[WikiLinks|WikiLink]] on the page into html
+links. The function is passed named parameters "page", "destpage", and
+"content". It should return the linkified content.  Present in IkiWiki 2.40
+and later.
+
+Plugins that implement linkify must also implement a scan hook, that scans
+for the links on the page and adds them to `%links`.
+
+### scan
+
+       hook(type => "scan", id => "foo", call => \&scan);
+
+This hook is called early in the process of building the wiki, and is used
+as a first pass scan of the page, to collect metadata about the page. It's
+mostly used to scan the page for WikiLinks, and add them to `%links`.
+Present in IkiWiki 2.40 and later.
+
+The function is passed named parameters "page" and "content". Its return
+value is ignored.
+
 ### htmlize
 
        hook(type => "htmlize", id => "ext", call => \&htmlize);
@@ -222,8 +246,11 @@ source files that were rendered.
 
 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 (including the http headers) and
-terminate the program.
+parameters, and if it will handle this CGI request, output a page
+(including the http headers) and terminate the program.
+
+Note that cgi hooks are called as early as possible, before any ikiwiki
+state is loaded, and with no session information.
 
 ### auth
 
@@ -334,10 +361,11 @@ next time ikiwiki is run. The hash holds per-page state, so to set a value,
 use `%pagestate{$page}{$id}{$key}=$value`, and to retrieve the value,
 use `%pagestate{$page}{$id}{$key}`.
 
-`$key` can be any string you like, but `$id` must be the same as the "id"
-parameter passed to `hook()` when registering the plugin. This is so
-ikiwiki can know when to delete pagestate for plugins that are no longer
-used.
+The `$value` can be anything that perl's Storable module is capable of
+serializing. `$key` can be any string you like, but `$id` must be the same
+as the "id" parameter passed to `hook()` when registering the plugin. This
+is so ikiwiki can know when to delete pagestate for plugins that are no
+longer used.
 
 When pages are deleted, ikiwiki automatically deletes their pagestate too.
 
@@ -478,11 +506,16 @@ If the destination directory doesn't exist, it will first be created.
 
 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.
+being rendered. 
+
+It's important to call this before writing to any file in the destination
+directory, and it's important to call it consistently every time, even if
+the file isn't really written this time -- unless you delete any old
+version of the file. In particular, in preview mode, this should still be
+called even if the file isn't going to be written to during the preview.
 
 Ikiwiki uses this information to automatically clean up rendered files when
-the page that rendered them goes away or is changes to no longer render
+the page that rendered them goes away or is changed to no longer render
 them. will_render also does a few important security checks.
 
 #### `pagetype($)`
@@ -495,12 +528,16 @@ a type that ikiwiki knowns how to htmlize. Otherwise, returns undef.
 Given the name of a source file, returns the name of the wiki page
 that corresponds to that file.
 
-#### `srcfile($)`
+#### `srcfile($;$)`
 
 Given the name of a source file in the wiki, searches for the file in
 the source directory and the underlay directories (most recently added
 underlays first), and returns the full path to the first file found.
 
+Normally srcfile will fail with an error message if the source file cannot
+be found. The second parameter can be set to a true value to make it return
+undef instead.
+
 #### `add_underlay($)`
 
 Adds a directory to the set of underlay directories that ikiwiki will