+
+> I have a plan for a way to avoid unecessary rebuilds caused by the
+> sidebar. The idea is to use wikistate to store what a sidebar renders to.
+> Then in the needsbuild hook, render sidebar(s) and compare with their
+> previous stored rendering. If a sidebar's rendered content has changed,
+> then all pages that display that sidebar need to be forced to be rebuilt.
+>
+> Also, if there is no previous stored rendering for a sidebar, or
+> if there is a stored rendering for a sidebar page that no longer exists, then
+> the pages need to be rebuilt. (This should deal with the [[bugs/Building_a_sidebar_does_not_regenerate_the_subpages]] bug.
+>
+> This would also save significant time, since the stored sidebar rendering
+> could just be dumped into the page by the pagetemplate hook. Current code
+> re-loads and renders the same sidebar file for every page built!
+>
+> The sticky part is (relative) links on the sidebar. These would need to
+> be modified somehow depending on the page that the sidebar is placed on,
+> to not break the link.
+>
+> Another wrinkle is changing subpage links on a sidebar. Suppose a sidebar
+> links to page `foo`. If page `bar/foo` exists, the sidebar on page bar will,
+> currently, link to that page, in preference to a toplevel `foo`.
+> If `bar/foo` is removed, it will update to link to `foo`. With the new
+> scheme, the stored sidebar rendering is not for page `foo`, and so
+> the change of the `bar/foo` link will not be noticed or acted on.
+> Granted, it's unlikely that anyone relies on the current behavior. You
+> generally want links on a sidebar to link to the same place on every page
+> that displays it. So finding some way to force all links on a sidebar to
+> be handled absolutely and documenting that would avoid this problem.
+>
+> So, one way to handle both the above problems would be to use the
+> pre-rendered sidebar for each page, but use a html parser to look for
+> links in it, and munge them to work as relative links on the page the
+> sidebar is being added to. Or, if the wiki's url is known, just do this
+> once when rendering the sidebar, adding the full url to the links.
+> (Maybe require `url` be set when using sidebar?)
+> --[[Joey]]