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.
+content is going to (different for inlined pages), and a "preview"
+parameter is set to a true value if the page is being previewed. 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
Logs a debugging message. These are supressed unless verbose mode is turned
on.
-#### `error($)`
+#### `error($;$)`
-Aborts with an error message.
+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
goes down the directory tree to the base looking for matching
pages, as described in [[SubPage/LinkingRules]].
-#### `htmllink($$$;$$$)`
+#### `htmllink($$$;@)`
Many plugins need to generate html links and add them to a page. This is
done by using the `htmllink` function. The usual way to call
some of the hook functions above; the ones that are not passed it are not used
during inlining and don't need to worry about this issue.
-The remaining three optional parameters to `htmllink` are:
+After the three required parameters, named parameters can be used to
+control some options. These are:
-1. noimageinline - set to true to avoid turning links into inline html images
-1. forcesubpage - set to force a link to a subpage
-1. linktext - set to force the link text to something
+* noimageinline - set to true to avoid turning links into inline html images
+* forcesubpage - set to force a link to a subpage
+* linktext - set to force the link text to something
+* anchor - set to make the link include an anchor
#### `readfile($;$)`
A failure to read the file will result in it dying with an error.
-#### `writefile($$$;$)`
+#### `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
+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.
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.