X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/f6fd7639daadea87530897ffd4882c970413822d..f0ed76441d94c9bec9ebc1314b81301fe179a7fc:/doc/plugins/write.mdwn

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index fe7cf0183..707622956 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -734,7 +734,10 @@ Additional named parameters can be specified:
 * `filter` is a reference to a function, that is called and passed a page,
   and returns true if the page should be filtered out of the list.
 * `sort` specifies a sort order for the list. See
-  [[ikiwiki/PageSpec/sorting]] for the avilable sort methods.
+  [[ikiwiki/PageSpec/sorting]] for the avilable sort methods. Note that
+  if a sort method is specified that depends on the
+  page content (such as 'meta(foo)'), the deptype needs to be set to
+  a content dependency.
 * `reverse` if true, sorts in reverse.
 * `num` if nonzero, specifies the maximum number of matching pages that
   will be returned.
@@ -960,8 +963,8 @@ will yield something like `foo/feed.rss`.
 This adds a link to `%links`, ensuring that duplicate links are not
 added. Pass it the page that contains the link, and the link text.
 
-An optional third parameter sets the link type (`undef` produces an ordinary
-[[ikiwiki/WikiLink]]).
+An optional third parameter sets the link type. If not specified,
+it is an ordinary [[ikiwiki/WikiLink]].
 
 ## Miscellaneous
 
@@ -1129,6 +1132,24 @@ For example, "backlink(foo)" is influenced by the contents of page foo;
 they match; "created_before(foo)" is influenced by the metadata of foo;
 while "glob(*)" is not influenced by the contents of any page.
 
+### Sorting plugins
+
+Similarly, it's possible to write plugins that add new functions as
+[[ikiwiki/pagespec/sorting]] methods. To achieve this, add a function to
+the IkiWiki::SortSpec package named `cmp_foo`, which will be used when sorting
+by `foo` or `foo(...)` is requested.
+
+The names of pages to be compared are in the global variables `$a` and `$b`
+in the IkiWiki::SortSpec package. The function should return the same thing
+as Perl's `cmp` and `<=>` operators: negative if `$a` is less than `$b`,
+positive if `$a` is greater, or zero if they are considered equal. It may
+also raise an error using `error`, for instance if it needs a parameter but
+one isn't provided.
+
+The function will also be passed one or more parameters. The first is
+`undef` if invoked as `foo`, or the parameter `"bar"` if invoked as `foo(bar)`;
+it may also be passed additional, named parameters.
+
 ### Setup plugins
 
 The ikiwiki setup file is loaded using a pluggable mechanism. If you look