map: Use a contentless dependency unless show= is specified.

This makes simple maps efficient enough that they can be used on sidebars!

IkiWiki/Plugin/map.pm

@@ -68,13 +68,13 @@ sub preprocess (@) {
 	}
 
 	# Needs to update whenever a page is added or removed (or in some
-	# cases, when its content changes, if show=title), so register a
-	# dependency.
-	add_depends($params{page}, $params{pages});
+	# cases, when its content changes, if show= is specified), so
+	# register a dependency.
+	add_depends($params{page}, $params{pages}, content => exists $params{show});
 	# Explicitly add all currently shown pages, to detect when pages
 	# are removed.
 	foreach my $item (keys %mapitems) {
-		add_depends($params{page}, $item);
+		add_depends($params{page}, $item, content => exists $params{show});
 	}
 
 	# Create the map.

debian/changelog

@@ -16,6 +16,8 @@ ikiwiki (3.14159266) UNRELEASED; urgency=low
   * pagecount: Use a contentless dependency, which makes this
     directive much less expensive to use, since page edits will
     no longer trigger an unnecessary update of the page count.
+  * map: Use a contentless dependency unless show= is specified.
+    This makes simple maps efficient enough that they can be used on sidebars!
 
  -- Joey Hess <joeyh@debian.org>  Sun, 27 Sep 2009 17:40:03 -0400