Re: Project - Eliminating grob parents and outside-staff-priority

[address@hidden]

On 30 sept. 2012, at 14:16, Janek Warchoł <address@hidden> wrote:

> Hi,
> 
> interesting discussion, i learn a lot.
> 
> On Sun, Sep 30, 2012 at 11:39 AM, David Kastrup <address@hidden> wrote:
>> Basically, a grob says "I want to have this and that information for
>> making my positioning" and LilyPond says "You can't get it right now".
>> Then the grob says "ok, I'll do a tentative positioning", and LilyPond
>> will come back with more information later and ask again.
> 
> I have no idea whether there are any not-very-experienced developers
> (or users) following this thread, but if they are, i'm sure this is a
> very nice and helpful explanation for them :)
> 
> cheers,
> Janek

Just to clarify things for anyone following the thread: this is not currently 
how LilyPond works, but I'm assuming what you're proposing is a suggestion for 
a model.

It's an interesting idea for grobs to ping a sort of central hive ("LilyPond" 
in your text above) to know what information they can access and when.  This'd 
require a major change to the architecture - currently, grobs specify in their 
request whether they want tentative or permanent information via the use of 
functions like Grob::pure_relative_y_coordinate versus 
Grob::relative_coordinate.  I'm worried about having a sort of centralized 
brain that tells grobs what they can and can't know - sounds Kafka-esque.  I 
like the decentralized model where grobs, via their callbacks, self-police for 
what information they need from other grobs and when it's ok to get it.

Cheers,
MS