Re: Access grob name?

[Simon Albrecht]

On 17.09.2015 14:20, David Kastrup wrote:
> Simon Albrecht <address@hidden> writes:
>
> > Hello,
> >
> > I’ve written a music function which applies some tweaks on dynamics to
> > offset them. Unfortunately, it’s not possible to use the offset music
> > function on X-offset, because it is a mutable property.
> What does that mean?  Any relation to issue 4516 here?

Obviously. I try to work around the technical limitation that you 
described in your last comment there.
Sorry for describing a superficial point of view again:
1. I need to tweak Y-offset of e.g. DynamicText.
2. If I use \tweak, the default calculation is _replaced_ by the new 
value. This makes it unpredictable, because the resulting offset, 
relative to the position without a tweak, is not equal to the value 
which I used in tweaking.
3. Thus I’d like to use \offset, so my offset is _added_ to the value 
returned by the default calculation.

But IIUC, the latter is impossible (? currently?) because the 
calculation is done only after the \offset could be applied. Is that 
anywhere near correct?

> > Thus I have to add a displacement for DynamicText so that it is not
> > aligned to its baseline, but to the ‘center’ like normally.  Now, it
> > would help if the music function could find out by itself whether to
> > apply this displacement, depending on which grob it is applied to. As
> > an example (attached also): %%%%%%%%%% \version "2.19.27"
> >
> > test =
> > #(define-music-function (ev) (ly:music?)
> >     (tweak 'color red ev))
> >
> > {
> >    c''-\test \> g'-\test \f
> > }
> > %%%%%%%%%%
> > How can I modify the function so that only the DynamicText is colored,
> > the Hairpin isn’t?
> Uh, (tweak '(DynamicText color) red ev) maybe?  Seems rather
> straightforward.

Oh, of course. My example was too simple then. Let’s say: I want to 
color all objects red, only DynamicText should be blue :-) Coined on 
offsets: Both need to be offset, but DynamicText needs an additional 
displacement.

Yours, Simon