Doc: Extending - rewrite - LilyPond Variables

Doc: Extending - rewrite - LilyPond Variables

Issue 4948

Last para of Extending/LP variables
rewrite for clarity.

[dak, 2016-07-31 17:09:56]

https://codereview.appspot.com/309820043/diff/1/Documentation/extending/schem...
File Documentation/extending/scheme-tutorial.itely (right):

https://codereview.appspot.com/309820043/diff/1/Documentation/extending/schem...
Documentation/extending/scheme-tutorial.itely:785: the variable's value.  For
that reason, music functions in LilyPond do
I'm pretty sure that I wrote this originally.  "Since" and "for that reason" is
both pretty misleading since the creation of a copy is not a _reason_ but an
_excuse_ for being allowed to modify arguments.

It's more like:
---
Scheme allows modifying complex expressions in-place, and LilyPond makes
extensive use of this when transforming music with music functions.  But when
music expressions are stored in variables rather than entered directly, the
usual expectation when passing them to music functions would be to keep the
original value unmodified.  So when referencing a music variable with leading
backslash as @code{\twentyFour}, LilyPond creates a copy of that variable's
music value for use in the surrounding music expression rather than using the
variable's value directly.

Therefore, Scheme music expressions written with...
---
Something like that, reworded until the reworder thinks it makes sense.

[pkx166h, 2016-08-03 17:35:20]

With David K's suggestions.

[pkx166h, 2016-08-03 17:36:06]

Thanks David.

https://codereview.appspot.com/309820043/diff/1/Documentation/extending/schem...
File Documentation/extending/scheme-tutorial.itely (right):

https://codereview.appspot.com/309820043/diff/1/Documentation/extending/schem...
Documentation/extending/scheme-tutorial.itely:785: the variable's value.  For
that reason, music functions in LilyPond do
On 2016/07/31 17:09:56, dak wrote:
> I'm pretty sure that I wrote this originally.  "Since" and "for that reason"
is
> both pretty misleading since the creation of a copy is not a _reason_ but an
> _excuse_ for being allowed to modify arguments.
> 
> It's more like:
> ---
> Scheme allows modifying complex expressions in-place, and LilyPond makes
> extensive use of this when transforming music with music functions.  But when
> music expressions are stored in variables rather than entered directly, the
> usual expectation when passing them to music functions would be to keep the
> original value unmodified.  So when referencing a music variable with leading
> backslash as @code{\twentyFour}, LilyPond creates a copy of that variable's
> music value for use in the surrounding music expression rather than using the
> variable's value directly.
> 
> Therefore, Scheme music expressions written with...
> ---
> Something like that, reworded until the reworder thinks it makes sense.

Done.

[pkx166h, 2017-03-19 19:04:05]

author James Lowe pkx166h@gmail.com
Sun, 31 Jul 2016 17:32:44 +0100 (17:32 +0100)
committer James Lowe pkx166h@gmail.com
Wed, 10 Aug 2016 17:23:08 +0100 (17:23 +0100)
commit 3025442087de8dd3f88736290887ced86e360c25