Use $a and $b for SortSpec cmp callbacks

IkiWiki.pm

@@ -1975,10 +1975,10 @@ sub sortspec_translate ($) {
 		if (exists $IkiWiki::SortSpec::{"cmp_$word"}) {
 			if (defined $params) {
 				push @data, $params;
-				$code .= "IkiWiki::SortSpec::cmp_$word(\@_, \$data[$#data])";
+				$code .= "IkiWiki::SortSpec::cmp_$word(\$data[$#data])";
 			}
 			else {
-				$code .= "IkiWiki::SortSpec::cmp_$word(\@_, undef)";
+				$code .= "IkiWiki::SortSpec::cmp_$word(undef)";
 			}
 		}
 		else {
@@ -2095,9 +2095,8 @@ sub pagespec_match_list ($$;@) {
 	}
 
 	if (defined $params{sort}) {
-		my $f = sortspec_translate($params{sort});
-
-		@candidates = sort { $f->($a, $b) } @candidates;
+		@candidates = IkiWiki::SortSpec::sort_pages($params{sort},
+			@candidates);
 	}
 
 	@candidates=reverse(@candidates) if $params{reverse};
@@ -2412,13 +2411,23 @@ sub match_ip ($$;@) {
 
 package IkiWiki::SortSpec;
 
-sub cmp_title {
-	IkiWiki::pagetitle(IkiWiki::basename($_[0]))
-	cmp
-	IkiWiki::pagetitle(IkiWiki::basename($_[1]))
+# This is in the SortSpec namespace so that the $a and $b that sort() uses
+# $IkiWiki::SortSpec::a and $IkiWiki::SortSpec::b, so that plugins' cmp
+# functions can access them easily.
+sub sort_pages
+{
+	my $f = IkiWiki::sortspec_translate(shift);
+
+	return sort $f @_;
 }
 
-sub cmp_mtime { $IkiWiki::pagemtime{$_[1]} <=> $IkiWiki::pagemtime{$_[0]} }
-sub cmp_age { $IkiWiki::pagectime{$_[1]} <=> $IkiWiki::pagectime{$_[0]} }
+sub cmp_title {
+	IkiWiki::pagetitle(IkiWiki::basename($a))
+	cmp
+	IkiWiki::pagetitle(IkiWiki::basename($b))
+}
+
+sub cmp_mtime { $IkiWiki::pagemtime{$b} <=> $IkiWiki::pagemtime{$a} }
+sub cmp_age { $IkiWiki::pagectime{$b} <=> $IkiWiki::pagectime{$a} }
 
 1

IkiWiki/Plugin/meta.pm

@@ -374,25 +374,23 @@ sub match_copyright ($$;@) {
 package IkiWiki::SortSpec;
 
 sub cmp_meta {
-	my $left = $_[0];
-	my $right = $_[1];
-	my $meta = $_[2];
+	my $meta = $_[0];
 	error(gettext("sort=meta requires a parameter")) unless defined $meta;
 
 	if ($meta eq 'updated' || $meta eq 'date') {
-		return IkiWiki::Plugin::meta::get_sort_key($left, $meta)
+		return IkiWiki::Plugin::meta::get_sort_key($a, $meta)
 			<=>
-			IkiWiki::Plugin::meta::get_sort_key($right, $meta);
+			IkiWiki::Plugin::meta::get_sort_key($b, $meta);
 	}
 
-	return IkiWiki::Plugin::meta::get_sort_key($left, $meta)
+	return IkiWiki::Plugin::meta::get_sort_key($a, $meta)
 		cmp
-		IkiWiki::Plugin::meta::get_sort_key($right, $meta);
+		IkiWiki::Plugin::meta::get_sort_key($b, $meta);
 }
 
 # A prototype of how sort=title could behave in 4.0 or something
 sub cmp_meta_title {
-	$_[2] = 'title';
+	$_[0] = 'title';
 	return cmp_meta(@_);
 }
 

IkiWiki/Plugin/sortnaturally.pm

@@ -25,8 +25,8 @@ sub checkconfig () {
 package IkiWiki::SortSpec;
 
 sub cmp_title_natural {
-	Sort::Naturally::ncmp(IkiWiki::pagetitle(IkiWiki::basename($_[0])),
-		IkiWiki::pagetitle(IkiWiki::basename($_[1])))
+	Sort::Naturally::ncmp(IkiWiki::pagetitle(IkiWiki::basename($a)),
+		IkiWiki::pagetitle(IkiWiki::basename($b)))
 }
 
 1;

doc/plugins/write.mdwn

@@ -1117,16 +1117,16 @@ Similarly, it's possible to write plugins that add new functions as
 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.
+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.
 
-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.
+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
 

t/pagespec_match_list.t

@@ -12,7 +12,7 @@ IkiWiki::checkconfig();
 {
 	package IkiWiki::SortSpec;
 
-	sub cmp_path { $_[0] cmp $_[1] }
+	sub cmp_path { $a cmp $b }
 }
 
 %pagesources=(