Re: How to get Staff context-id from a grob?

[David Kastrup]

Jan Rosseel <address@hidden> writes:

> Urs Liska <ul <at> openlilylib.org> writes:
>
>> 
>> 
>>     Am 11.10.2013 10:22, schrieb Jan
>>       Rosseel:
>> 
>>     
>>     I don't know, but how do you want your solution to behave when you
>>     use << some music>> in more than one staff?
>>     Urs
>
> Quite simply: I didn't care about that situation because I never have that
> happening in the way I build a score. 
>
> But to answer the question: if the music gets instantiated in multiple Staff
> contexts, I will have multiple grobs and having the context ID would allow
> me to figure out in what context the music was used, and would thus allow me
> to direct my annotation to the right place. 
>
> Thinking of it: the case you mentioned kind of destroys my alternative
> solution I had in mind. So I really should find a way to attach that bit of
> information to a grob during the engraving process. 

Ok, here is another approach: the grob itself does not carry the
required information, but the grob_info data structure used for
acknowledging grobs carries the information about the engraver which
created the grob, and of course an engraver has a related context.

So if you do
\layout {
  \context {
    \Score
    \consists
    #(make-engraver
      (acknowledgers
        ((grob-interface engraver grob source-engraver)
         ...)))
  }
}

then ... is called when any grob is created, and
(ly:translator-context source-engraver) should give the context where
the grob has been created.  You can then record this relation in the
grob, or you can record it in a key-weak hashtable mapping grobs to
originating contexts.

Sorry, this feedback is a bit late...

-- 
David Kastrup