Issue 3991: \magnifyMusic - reluctantly surrender to issues 3987 and 3990.

http://code.google.com/p/lilypond/issues/detail?id=3991

Until issues 3987 and 3990 are fixed, \magnifyMusic is broken, so I'm turning off some of the intended functionality, and putting a note in the docs.

Related issues:
inconsistent spacing with spacing-increment
http://code.google.com/p/lilypond/issues/detail?id=3987

\newSpacingSection + change fontSize = mess
http://code.google.com/p/lilypond/issues/detail?id=3990

[pkx166h, 2014-07-05 04:33:57]

https://codereview.appspot.com/101690043/diff/20001/Documentation/notation/ed...
File Documentation/notation/editorial.itely (right):

https://codereview.appspot.com/101690043/diff/20001/Documentation/notation/ed...
Documentation/notation/editorial.itely:310: \magnifyMusic @var{mag} {
I think this is breaking make, you need to escape the @ and { and } signs in an
@example. @@var@{mag@}, the same lower down.

[pwm, 2014-07-05 14:17:23]

Happened to see another little simplification.

https://codereview.appspot.com/101690043/diff/40001/scm/music-functions.scm
File scm/music-functions.scm (right):

https://codereview.appspot.com/101690043/diff/40001/scm/music-functions.scm#n...
scm/music-functions.scm:2452: (lambda (x) x)))
Can be simplified: (lambda (x) x) is the same as x

[Mark Polesky, 2014-07-05 16:58:38]

On 2014/07/05 14:17:23, pwm wrote:
> Happened to see another little simplification.
> ...
> Can be simplified: (lambda (x) x) is the same as x

Not in this case; guile would complain about unbound variable x.  I could have
used the guile function `identity', but I opted not to since it's not documented
in the guile manual.  I'll rewrite it though, so that the `if' clause is inside
the `lambda'.  But I'll do that in the Issue 3942 patch set
(http://codereview.appspot.com/103890046/).

Thanks

[dak, 2014-07-06 13:04:12]

https://codereview.appspot.com/101690043/diff/40001/scm/music-functions.scm
File scm/music-functions.scm (right):

https://codereview.appspot.com/101690043/diff/40001/scm/music-functions.scm#n...
scm/music-functions.scm:2452: (lambda (x) x)))
On 2014/07/05 14:17:23, pwm wrote:
> Can be simplified: (lambda (x) x) is the same as x  

Uh, no?

(lambda (x) x) is the same as the function `identity'.  It most definitely is
the same as x only in extraordinary circumstances.

[dak, 2014-07-06 13:06:07]

On 2014/07/05 16:58:38, Mark Polesky wrote:
> On 2014/07/05 14:17:23, pwm wrote:
> > Happened to see another little simplification.
> > ...
> > Can be simplified: (lambda (x) x) is the same as x
> 
> Not in this case; guile would complain about unbound variable x.  I could have
> used the guile function `identity', but I opted not to since it's not
documented
> in the guile manual.

It is not documented in the GUILEv1 manual, but it *is* documented in the
GUILEv2 manual, so it is not going to go away.