[pmwiki-users] hierarchical groups, revisited

Joachim Durchholz jo at durchholz.org
Fri May 26 11:28:03 CDT 2006

John McGinnis schrieb:
> The discussion to date seems to revolve around the relationship of  link 
> references between subgroups. But I don’t know if that is all the issues 
> as the initial discussions of [[Animal.Feline]] have indicated.

Maybe not, but it's a really hard problem. (Well, it would be easy to 
slap some solution, but it's hard to solve it *well*.)

That's why we're concentrating on that one right now.
(That doesn't mean that additional ideas are unwelcome, or don't help 
decide about the value of some idea.)

 > The hierarchy structure needs to be a tad more flexible.

> Assume something for a moment, I have the following structure with all 
> pages in the Group Vehicles:

The formatting was screwed; I hope the following correction is what you 

> Cars  . Buick . Electra
>               . LaSabre
>               . Lucerine
>       . GMC . Tahoe
>       . Chevy . Camaro
>               . Caprice
> But now I want to have an overlay like this:
> Cars . Full Size . Electra
>                  . Tahoe
>                  . Caprice
>                  . (Entries from other car mfrs)

You can set that up by creating the leaf pages as redirects to the 
standard pages.

> Presumably one can derive both hierarchies without regenerating all the 
> supporting pages. Worse yet, entries GM, Buick, GMC, Chevy, and Full 
> Size should be assumed to be wiki pages as well without any group 
> dependencies derived from the prior hierarchy.

Solved by hierarchy.
Well, you'll have CarsByManufacturer and CarsBySize on the root page of 
each category (and most likely these won't be root pages but part of 
some larger hierarchy). But I think you can get what you want.

Actually that's independent of the hierarchy discussion. You want 
aliases; redirects solve that problem. (Well, to a large part at least; 
people following a virtual hierarchy will find themselves in another 
group than they expected, but hey, that would happen even if the aliases 
were not faked by redirects.)

>     * Attribute inheritance (or not, user option) to child from parent.
>       The page layout for example could be inherited from Full Size
>       rather than from Buick for the page Electra.

Group-specific templates. (If would be nice if these were wiki pages, 
but I see no special difficulties other than that.)
With redirects, that wouldn't help with the leaf pages, of course.

>     * Hierarchical references are independent of the usual page syntax.
>       I think it should be inherent that in referencing the pages one is
>       not making a normal wiki page reference. Something like [# … #]
>       than [[../<some page>]]. Visual inspection should tell the author
>       this is not a relative link.

Actually I think it should be the other way round: hierarchical 
references should be part of the usual page syntax (whatever "usual page 
syntax" will be at that point).
I may be misunderstanding what you mean with a "hierarchical reference".

>     * Precedence. I would hazard that if an existing page is included in
>       a hierarchy that the preference would be that in the event that
>       there are page directives that conflict, that the directive from
>       the hierarchy wins.

Whatever a proposed system does: if it needs this kind of precedence, 
it's doomed. Such systems have the property that adding a page can 
change the interpretation of links in unrelated pages; I don't even want 
to imagine the ensuing madness.

>     * Hierarchical definition would appear in Search and (:pagelist:)
>       results like any other group:pages.

Again, I think I don't understand what you meant when you said 


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