Issue 2179 in lilypond: Improve warnings about spanners/lyrics etc. cannot be set from 'outside' to 'inside' << {...} \\ {...} >> constructs

[lilypond]

Status: Accepted
Owner: ----
Labels: Type-Documentation

New issue 2179 by address@hidden: Improve warnings about spanners/lyrics  
etc. cannot be set from 'outside' to 'inside' << {...} \\ {...} >>  
constructs
http://code.google.com/p/lilypond/issues/detail?id=2179

From thread

http://lists.gnu.org/archive/html/lilypond-user/2012-01/msg00046.html

--snip--

> \version "2.12.2"
> {
>        <c' a>4 <e' c'> <g' e'> <b' g'> << { b'1 } \\ { g'4( f' e'2) } >>
> }
> \addlyrics {
>        Ex -- cel -- lent Thy name! % The last word does not appear
> }

The problem is that the double backslash automagically creates _two_ new  
voices; you only want one, with the other being a continuation of the  
original voice.  The solution is to create the new voice explicitly:

{
       <c' a>4 <e' c'> <g' e'> <b' g'> << {\voiceOne b'1 } \new Voice {  
\voiceTwo g'4( f' e'2) } >>
}
\addlyrics {
       Ex -- cel -- lent Thy name! % The last word does now appear
}

(The \voiceOne and \voiceTwo don't affect the lyrics, only the note stems.)

> The music I am typesetting is four-part harmony

In that case, personally, I'd write it as four parts rather than as chords.

--snip--

and then

--snip--
On 4 January 2012 23:32, Carl Sorensen <address@hidden> wrote:

> Please see the Notation Reference, section 1.5.2.  In particular, look at
> Temporary polyphonic passages.

This problem pops up often.  I remember having replied to dozens of e-mails
—both on the French users mailing list and on lilypond-user— from
confused users about this.  This is indeed explained in the notation
reference that

 "[The << {...} \\ {...} >> construct] behaves differently to the
 similar construct without the double backslashes: all the expressions
 within this construct are assigned to new Voice contexts."

but could it be added that this implies the (dynamic) spanners, lyrics
associated to voice, etc. cannot be used from outside to inside the
<< {...} \\ {...} >> construct (and vice versa)?
And would it be possible to put a "warning box" or so around this?
Maybe we could add also a similar warning in the learning manual,
LM 3.2.1 I’m hearing Voices.

What do you think?  James?

Of course the best would be to "solve" issue #1316 …
http://code.google.com/p/lilypond/issues/detail?id=1316

--snip--