Use $a and $b for SortSpec cmp callbacks

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

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index de2b47015a6f5e8b4ce9a79178ef2a22edca76f4..f42cc86ae29bc00f26ed655d57bf2f83adbb3869 100644 (file)
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -1114,24 +1114,19 @@ while "glob(*)" is not influenced by the contents of any page.
 
 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::PageSpec package named `cmp_foo`, which will be used when sorting
+the IkiWiki::SortSpec package named `cmp_foo`, which will be used when sorting
 by `foo` or `foo(...)` is requested.
 
-The function will be passed three or more parameters. The first two are
-page names, and the third is `undef` if invoked as `foo`, or the parameter
-`"bar"` if invoked as `foo(bar)`. It may also be passed additional, named
-parameters.
-
-It should return the same thing as Perl's `cmp` and `<=>` operators: negative
-if the first argument is less than the second, positive if the first argument
-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.
-
-You can also define a function called `check_cmp_foo` in the same package.
-If you do, it will be called while preparing to sort by `foo` or `foo(bar)`,
-with argument `undef` or `"bar"` respectively; it may raise an error using
-`error`, if sorting like that isn't going to work.
+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