path: root/doc/bugs/pagetitle_function_does_not_respect_meta_titles.mdwn

[[!tag patch plugins/inline patch/core]]
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.




A few quick notes about it:



Using inline 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:


It needs the full page name, not basename.


titlepage(pagetitle($page)) reversability.


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.


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 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
is the parent of this page
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
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:

never display any modified page title in links; this is the
current behaviour, and we should keep it as the default one
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 :)
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]]