ikiwiki/doc/bugs/pagetitle_function_does_not_respect_meta_titles.mdwn

The `IkiWiki::pagetitle` function does not respect title changes via `meta.title`. It really should, so that links rendered with `htmllink` get the proper title in the link text.

--[[madduck]]

----

It is possible to set a Page-Title in the meta-plugin, but that one isn't
reused in parentlinks. This [[patch]] may fix it.

<ul>
<li> I give pagetitle the full path to a page.
<li> I redefine the 'pagetitle'-sub to deal with it.
<li> to maintain compatibility for IkiWikis without the meta-plugin, i added a 'basename' to the Original-pagetitle.
</ul>

<pre>
diff -c /usr/share/perl5/IkiWiki/Render.pm.distrib /usr/share/perl5/IkiWiki/Render.pm
*** /usr/share/perl5/IkiWiki/Render.pm.distrib  Wed Aug  6 07:34:55 2008
--- /usr/share/perl5/IkiWiki/Render.pm  Tue Aug 26 23:29:32 2008
***************
*** 102,108 ****
        $template->param(
                title => $page eq 'index' 
                        ? $config{wikiname} 
!                       : pagetitle(basename($page)),
                wikiname => $config{wikiname},
                content => $content,
                backlinks => $backlinks,
--- 102,108 ----
        $template->param(
                title => $page eq 'index' 
                        ? $config{wikiname} 
!                       : pagetitle($page),
                wikiname => $config{wikiname},
                content => $content,
                backlinks => $backlinks,

diff -c /usr/share/perl5/IkiWiki/Plugin/parentlinks.pm.distrib /usr/share/perl5/IkiWiki/Plugin/parentlinks.pm
*** /usr/share/perl5/IkiWiki/Plugin/parentlinks.pm.distrib      Wed Aug  6 07:34:55 2008
--- /usr/share/perl5/IkiWiki/Plugin/parentlinks.pm      Tue Aug 26 23:19:43 2008
***************
*** 44,50 ****
                        "height_$height" => 1,
                };
                $path.="/".$dir;
!               $title=IkiWiki::pagetitle($dir);
                $i++;
        }
        return @ret;
--- 44,50 ----
                        "height_$height" => 1,
                };
                $path.="/".$dir;
!               $title=IkiWiki::pagetitle($path);
                $i++;
        }
        return @ret;

diff -c /usr/share/perl5/IkiWiki.pm.distrib /usr/share/perl5/IkiWiki.pm
*** /usr/share/perl5/IkiWiki.pm.distrib Wed Aug  6 07:48:34 2008
--- /usr/share/perl5/IkiWiki.pm Tue Aug 26 23:47:30 2008
***************
*** 792,797 ****
--- 792,799 ----
        my $page=shift;
        my $unescaped=shift;
  
+       $page=basename($page);
+ 
        if ($unescaped) {
                $page=~s/(__(\d+)__|_)/$1 eq '_' ? ' ' : chr($2)/eg;
    	}

diff -c /usr/share/perl5/IkiWiki/Plugin/meta.pm.distrib /usr/share/perl5/IkiWiki/Plugin/meta.pm
*** /usr/share/perl5/IkiWiki/Plugin/meta.pm.distrib     Wed Aug  6 07:34:55 2008
--- /usr/share/perl5/IkiWiki/Plugin/meta.pm     Tue Aug 26 23:30:58 2008
***************
*** 3,8 ****
--- 3,9 ----
  package IkiWiki::Plugin::meta;
  
  use warnings;
+ no warnings 'redefine';
  use strict;
  use IkiWiki 2.00;
  
***************
*** 289,294 ****
--- 290,319 ----
        }
  }
  
+ sub IkiWiki::pagetitle ($;$) {
+       my $page=shift;
+       my $unescaped=shift;
+ 
+       if ($page =~ m#/#) {
+               $page =~ s#^/##;
+               $page =~ s#/index$##;
+               if ($pagestate{"$page/index"}{meta}{title}) {
+                       $page = $pagestate{"$page/index"}{meta}{title};
+               } else {
+                       $page = IkiWiki::basename($page);
+               }
+       }
+ 
+       if ($unescaped) {
+               $page=~s/(__(\d+)__|_)/$1 eq '_' ? ' ' : chr($2)/eg;
+       }
+       else {
+               $page=~s/(__(\d+)__|_)/$1 eq '_' ? ' ' : "&#$2;"/eg;
+       }
+ 
+       return $page;
+ }
+ 
  package IkiWiki::PageSpec;
  
  sub match_title ($$;@) {

</pre>

----

> A few quick notes about it:

> - Using <code>inline</code> would avoid the redefinition + code duplication.
> - A few plugins would need to be upgraded.
> - It may be necessary to adapt the testsuite in `t/pagetitle.t`, as well.
>
> --[[intrigeri]]
>
>> It was actually more complicated than expected. A working prototype is
>> now in my `meta` branch, see my userpage for the up-to-date url.
>> Thus tagging [[patch]]. --[[intrigeri]]
>>
>>> Joey, please consider merging my `meta` branch. --[[intrigeri]]

So, looking at your meta branch: --[[Joey]] 

* Inter-page dependencies. If page A links to page B, and page B currently
  has no title, then A will display the link as "B". Now page B is modified
  and a title is added. Nothing updates "A".
  The added overhead of rebuilding every page that links to B when B is
  changed (as the `postscan` hook of the po plugin does) is IMHO a killer.
  That could be hundreds or thousands of pages, making interactive editing
  way slow. This is probably the main reason I had not attempted this whole
  thing myself. IMHO this calls for some kind of intellegent dependency
  handler that can detect when B's title has changed and only rebuild pages
  that link to B in that case.
* Looks like some plugins that use `pagetitle` to format it for display
  were not changed to use `nicepagetitle` (for example, rename).
  But most of those callers intend to display the page name
  as a title, but including the parent directories in the path. (Ie,
  "renaming foo/page title to bar/page title" -- 
  you want to know it's moved from foo to bar.) `nicepagetitle` does not
  allow doing that since it always takes the `basename`.
* I don't like the name `nicepagetitle`. It's not very descriptive, is it?
  And it seems very confusing to choose whether to use the "nice" or original
  version. My hope is that adding a second function is unnecessary.
  As I understand it, you added a new function for two reasons: 
  1) It needs the full page name, not basename.
  2) `titlepage(pagetitle($page))` reversability.
  
  1) If you look at all the callers
  Of `pagetitle` most of them pass a complete page name, not just the
  basename. In most cases `pagetitle` is used to display the full name
  of the page, including any subdirectory it's in. So why not just make
  it consitently be given the full name of the page, with another argument
  specifying if we want to get back just the base name.

  2) I can't find any code that actually uses the reversability like that.
  The value passed to `titlepage` always comes from some external
  source. Unless I missed one.
* The use of `File::Spec->rel2abs` is a bit scary.
* Does it really make sense to call `pagetitle` on the meta title
  in meta's `nicepagetitle`? What if the meta title is something like
  "foo_bar" -- that would be changed to "foo bar".
* parentlinks is changed to use `nicepagetitle(bestlink($page, $path))`.
  Won't `bestlink` return "" if the parent page in question does not exist?
* `backlinks()` is changed to add an additional `title` field
  to the hash returned, but AFAICS this is not used in the template.
* Shouldn't `Render.pm` use nicepagetitle when getting the title for the
  page template? Then meta would not need to override the title in the
  `pagetemplate` hook. (Although this would eliminate handling of
  `title_overridden` -- but that is little used and would not catch
  all the other ways titles can be overridden with this patch anyway.)