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.)

> I'm not a reviewer or anything, but can I chime in on changes to pagetitle?
> I don't think having meta-titles in wikilinks and the parentlinks path by
> default is necessarily a good thing. I don't consider the meta-title of a page
> as used in `<title>` to be the same thing as the short title you
> want in those contexts - IMO, the meta-title is the "formal" title of the page,
> enough to identify it with no other context, and frequently too long to be used
> as a link title or a parentlink, whereas the parentlinks title in particular
> should be some abbreviated form that's enough to identify it in context.
> [tbm](http://www.cyrius.com/) expressed a similar opinion when I was discussing
> ikiwiki with him at the weekend.
>
> It's a matter of taste whether wikilinks are "like a parentlink" or "like a
> `<title>`"; I could be persuaded either way on that one.
>
> An example from my site: [this page](http://www.pseudorandom.co.uk/2004/debian/ipsec/)
> is the parent of [this page](http://www.pseudorandom.co.uk/2004/debian/ipsec/wifi/)
> with a title too long to use in the latter's parentlinks; I think the titles of
> both those pages are too long to use as wikilink text too. Similarly, tbm's page
> about [Debian on Orion devices from Buffalo](http://www.cyrius.com/debian/orion/buffalo/)
> can simply be called "Buffalo" in context.
>
> Having a `\[[!meta abbrev="..."]]` that took precedence over title
> in parentlinks and possibly wikilinks might be a good way to fix this? Or if your
> preference goes the other way, perhaps a `\[[!meta longtitle=""]]` could take
> precedence when generating the `<title>` and the title that comes after the
> parentlinks. --[[smcv]]

>> I think you've convinced me. (I had always had some doubt in my mind as
>> to whether using titles in all these other places would make sense.)
>> 
>> Instead of meta abbrev, you could have a meta pagename that
>> overrides the page name displayed everywhere (in turn overridden by
>> meta title iff the page's title is being displayed). But is this complexity
>> needed? We have meta redir, so if you want to change the name of a page,
>> you can just rename it, and put in a stub redirection page so links
>> still work.
>> 
>> This leaves the [[plugins/contrib/po]] plugin, which really does need
>> a way to change the displayed page name everywhere, and at least a
>> subset of the changes in the meta branch are needed to support that.
>> 
>> (This would also get around my concern about inter-page dependency
>> handling, since po contains a workaround for that, and it's probably
>> acceptable to use potentially slow methods to handle this case.)
>> --[[Joey]] 

>>> I'm glad to implement whatever decision we'll make, but I don't
>>> clearly understand what this discussion's conclusion is. It seems
>>> like we agree at least on one point: meta page titles shall not be
>>> displayed all over the place by default; I have therefore disabled
>>> `meta_overrides_page_title` by default in my `meta` branch.
>>> 
>>> My next question is then: do we only want to satisfy the `po`
>>> plugin needs? Or do we want to allow people who want this, such as
>>> [[madduck]], to turn on a config switch so that meta page titles
>>> are displayed as wikilinks titles? In the latter case, what level
>>> of configurability do we want? I can think of a quite inelegant
>>> way to implement full configurability, and provide a configuration
>>> switch for every place where links are displayed, such as
>>> wikilinks, parentlinks, etc., but I don't think the added bonus is
>>> worth the complexity of it.
>>> 
>>> I think we can roughly split the needs into three categories:
>>> 
>>> 1. never display any modified page title in links; this is the
>>>    current behaviour, and we should keep it as the default one
>>> 2. display modified page titles only at well chosen places; that
>>>    could be "manual" wikilinks, I mean those generated by the
>>>    `link`, `camelcase` & al. plugins, the recentchanges page, and
>>>    maybe a few other places; keep the usual pagename-based title
>>>    for every other link, such as the parentlinks ones.
>>>    The inter-page dependency problem remains, though. As a first
>>>    step, I'm in favour of the "slow, but correct" implementation,
>>>    with a big warning stating that enabling this option can make
>>>    a wiki really sluggish; if someone really wants this to work
>>>    fast, he/she'll implement a clever dependency handler :)
>>> 3. display modified page titles all over the place; IMHO, we
>>>    should implement only the bits needed so that the `po` plugin
>>>    can set this up, rather than provide this as
>>>    a user-configurable option.
>>> 
>>> So my question is: do we want to implement the #2 case, or not?
>>> I propose myself to only implement #1 and #3 to start with, but do
>>> it in a way that leaves room for #2.
>>> 
>>> --[[intrigeri]]
>>>
>>>> I agree, we should concentrate on getting just enough functionality
>>>> for the po plugin, because I want to merge the po plugin soon.
>>>> If #2 gets tackled later, we will certianly have all kinds of fun.
>>>> no matter what is done for the po plugin. --[[Joey]]