-### sort
-
- hook(type => "sort", id => "foo", call => \&sort_by_foo);
-
-This hook adds an additional [[ikiwiki/pagespec/sorting]] order or overrides
-an existing one.
-
-The callback is given two page names followed by the parameter as arguments, and
-returns negative, zero or positive if the first page should come before,
-close to (i.e. undefined order), or after the second page.
-
-For instance, the built-in `title` sort order could be reimplemented as
-
- sub sort_by_title {
- pagetitle(basename($_[0])) cmp pagetitle(basename($_[1]));
- }
-
-and to sort by an arbitrary `meta` value, you could use:
-
- # usage: sort="meta(description)"
- sub sort_by_meta {
- my $param = $_[2];
- error "sort=meta requires a parameter" unless defined $param;
- my $left = $pagestate{$_[0]}{meta}{$param};
- $left = "" unless defined $left;
- my $right = $pagestate{$_[1]}{meta}{$param};
- $right = "" unless defined $right;
- return $left cmp $right;
- }
-