Re: Create \temporary for doing overrides without pop-first set (issue 6687044)

[Thomas Morley]

Hi,

some thoughts from a user's POV:

I didn't know anything about pop, push, clear and stack before.
Ok, I wondered what the output of
\displayMusic \override NoteHead #'color = #blue
should mean:

   (make-music
     'ContextSpeccedMusic
     'context-type
     'Bottom
     'element
     (make-music        
       'OverrideProperty       <=
       'pop-first              <=
       #t                      <=
       'grob-property-path
       (list (quote color))
       'grob-value
       (list 0.0 0.0 1.0)
       'symbol
       'NoteHead))

but it never hindered me. :)

Well, a friend (experienced developer, pitty, he's not interested in
LilyPond) explained pop, push, clear and stack to me.
It took him less than 5 minutes and I'm quite sure I understood, at
least the basics.
(Ok, perhaps I'm not the average-user, I do like scheme and I was
always interested in mathematics.)

I have no doubts that there are more users like me. So I'd vote for
documenting all the stuff in the NR.
IIUC, with the current proposal of \temporary on Rietveld, nothing of
the old behaviour is changed, but we get a new possibility.
So I'm all for it.

One tiny thing.
I'm not sure if \temporary is the best naming, because one could think
that temporary implicates an end or some time-limitation.
With a music-function like

cN =
#(define-music-function (parser location color music)(scheme? ly:music?)
#{
        \temporary \override NoteHead #'color = $color
        $music
#})

\relative c' {
        \cN #red
        { c1 }
        d
}

the color-override is _not_ limited to { c1 }

Well, it's absolute clear to me why it is not limited and I _don't_
want to propose it, but I think \temporary could be misunderstood this
way.

It should be enough to clearify this with proper documentation.
Alternative would be renaming, but I don't have a better proposal.

OTOH, if another approach, the more direct \push \pop \clear (or sth
similiar) is discussed, please don't think documentation of it would
be too complicated or too much explaining programming-basics for
users.

-Harm