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.
+
## Types of hooks
In roughly the order they are called.
make arbitrary changes. The function is passed named parameters `page` and
`content` and should return the filtered content.
+### scan
+
+ hook(type => "scan", id => "foo", call => \&scan);
+
+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
+
### preprocess
Adding a [[PreProcessorDirective]] is probably the most common use of a
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
+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.