Re: [patch] \label, page references

[Han-Wen Nienhuys]

Nicolas Sceaux escreveu:
> Hi,
> 
> Here is a patch implementing a page reference markup feature.

Hi,

I'm missing a test file.

I have a couple of concerns:

 - the final evaluation happens with \layout{} block for a \score 
marker, no?  Wouldn't it be cleaner to look at the 

> A label is attached to a score or a top-level markup using a \label
> command with a symbol argument.  When the page breaking is done, a {
> label -> page-number } table is filled, which can be referenced later to
> retreive page numbers from a label.  The patch introduces a new stencil
> command, delay-stencil-evaluation, and a new markup command using it:
> \page-ref.


> +       else if (Prob * markup = unsmob_prob (scm_car (l)))
> +         labels = markup->get_property ("labels");
> +

This looks fishy; the type checking should be stricter, music is a prob too.

> +  book_->paper_->set_variable (ly_symbol2scm ("label-page-table"), 
> +                            scm_reverse_x (label_page_table, SCM_EOL));

This is acceptable if there is no other way, but I would like the rendering 
process to be a function, ie. in the ideal case, the rendering should not write 
into the Output_def. Can you think of a way to store this information elsewhere,
or pass it as a parameter to the delayed evaluation? You may need to extend the
stencil evaluation process to have another parameter.

> +void
> +set_label (SCM sys, SCM label)
> +{
> +  if (Paper_score *ps = dynamic_cast<Paper_score*> (unsmob_music_output 
> (sys)))
> +    {
> +      SCM labels = ps->layout ()->c_variable ("labels");
> +      ps->layout ()->set_variable (ly_symbol2scm ("labels"),
> +                                scm_cons (label, labels));
> +    }
> +  else if (Prob *pb = unsmob_prob (sys))

idem.

>  
> +      /* set the first system labels with the score ones */
> +      if (i == 0)
> +     {
> +       SCM labels = pscore_->layout ()->c_variable ("labels");
> +       system->set_property ("labels", labels);
> +     }

Wouldn't it be more appropriate to set labels for each broken
System, so you could eg. refer to the page number of a rehearsal
mark?  It would be difficult to transport the label symbol out of 
the initial markup -> stencil conversion, though. You might have to
run a separate pass over all nested markups to discover the labels.



Final remark: despite my comments, I think this is way cool!

-- 

Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen