Doc: NR Clarify finer point of repeat unfold

Doc: NR Clarify finer point of repeat unfold

This is for tracker issue 1801.

Explain as an example, that \repeat unfold 2 {music expression} is
not always the same as writing out the music expression twice - especially
in a \relative context.

[janek, 2011-09-21 07:33:54]

LGTM.

From what i see, the surprise in this behaviour comes from two meanings of
"music expression" - it can be understood as "a piece of ly input" or "a piece
of music".  Shall we write a sentence about this difference?  I.e. "Using
\repeat unfold is equal to writing out a fragment of music several times over,
not a fragments of ly input"?

cheers,
Janek

[dak, 2011-09-21 08:02:47]

janek.lilypond@gmail.com writes:

> LGTM.
>
> From what i see, the surprise in this behaviour comes from two meanings
> of "music expression" - it can be understood as "a piece of ly input" or
> "a piece of music".  Shall we write a sentence about this difference?
> I.e. "Using \repeat unfold is equal to writing out a fragment of music
> several times over, not a fragments of ly input"?

If you write

blurb = { c e g a }

{ \blurb \relative c'' \blurb }

is \blurb a fragment of music, or a fragment of ly input?  I am afraid
it is both: relativable music is a weird thing.

And
\relative c' { \blurb \blurb }
is different from
\relative c' \repeat unfold 2 \blurb

The reason that it is different is not that one is "ly input" and the
other is "music", but that making \repeat unfold do something different
from \repeat volta would be a total nuisance, and so we _explicitly_
programmed this case to behave differently.

> http://codereview.appspot.com/5075047/

-- 
David Kastrup

[janek, 2011-09-21 08:31:12]

2011/9/21 David Kastrup <dak@gnu.org>:
> janek.lilypond@gmail.com writes:
>
>> LGTM.
>>
>> From what i see, the surprise in this behaviour comes from two meanings
>> of "music expression" - it can be understood as "a piece of ly input" or
>> "a piece of music".  Shall we write a sentence about this difference?
>> I.e. "Using \repeat unfold is equal to writing out a fragment of music
>> several times over, not a fragments of ly input"?
>
> If you write
>
> blurb = { c e g a }
>
> { \blurb \relative c'' \blurb }
>
> is \blurb a fragment of music, or a fragment of ly input?  I am afraid
> it is both: relativable music is a weird thing.
>
> And
> \relative c' { \blurb \blurb }
> is different from
> \relative c' \repeat unfold 2 \blurb
>
> The reason that it is different is not that one is "ly input" and the
> other is "music", but that making \repeat unfold do something different
> from \repeat volta would be a total nuisance, and so we _explicitly_
> programmed this case to behave differently.

Good point, you are right that it was nonsense.

cheers,
Janek

[Graham Percival (old account), 2011-09-21 19:32:52]

LGTM.

[Trevor Daniels, 2011-09-23 23:32:36]

LGTM

[pkx166h, 2011-09-24 02:16:37]

commit	f84eab93e732ed2b9aa50436202a28f34243c6

closing issue