Issue 4467: Auto_change_iterator: move some state from C++ to Scheme

This simplifies the iterator and prepares it for future combination
with partcombine code.

[thomasmorley651, 2015-06-29 09:03:56]

Some remarks.
Not related to your changes, though, why not fix them, when you're already on
it?

https://codereview.appspot.com/248470043/diff/1/scm/autochange.scm
File scm/autochange.scm (right):

https://codereview.appspot.com/248470043/diff/1/scm/autochange.scm#newcode2
scm/autochange.scm:2: 
This file is missing the usual remarks about license,

https://codereview.appspot.com/248470043/diff/1/scm/autochange.scm#newcode38
scm/autochange.scm:38: (m1 (make-non-relative-music (context-spec-music music
'Voice "one")))
If I'm not mistaken the local variable 'm1' isn't used. Delete his line!?

https://codereview.appspot.com/248470043/diff/1/scm/autochange.scm#newcode41
scm/autochange.scm:41: (evs (car context-list))
same with 'evs'

[Dan Eble, 2015-06-29 12:23:36]

https://codereview.appspot.com/248470043/diff/1/scm/autochange.scm
File scm/autochange.scm (right):

https://codereview.appspot.com/248470043/diff/1/scm/autochange.scm#newcode38
scm/autochange.scm:38: (m1 (make-non-relative-music (context-spec-music music
'Voice "one")))
On 2015/06/29 09:03:56, thomasmorley651 wrote:
> If I'm not mistaken the local variable 'm1' isn't used. Delete his line!?

Another possibility is that it was intended to be used, but by mistake it
wasn't, so that there are undiscovered bugs.

I'll try to consider this later today, but I'm not promising to change anything.

Thanks for your review.

[Dan Eble, 2015-07-02 12:36:04]

I haven't yet reached an understanding of what should be done about
make-non-relative-music.  Some testing would help me understand more deeply why
it is good for partcombine and whether it would be good for autochange, but I
have been short on time.  It's on my to-do list, but I do not want to delay this
patch for it.

[Dan Eble, 2015-07-03 00:54:27]

On 2015/07/02 12:36:04, Dan Eble wrote:
> I haven't yet reached an understanding of what should be done about
> make-non-relative-music.

After some testing, I understand that make-non-relative-music should have been
used within \autochange.  I've posted a patch in
https://codereview.appspot.com/250170043/ .  Thanks for finding that defect,
Thomas.

[thomasmorley651, 2015-07-03 10:25:52]

On 2015/07/03 00:54:27, Dan Eble wrote:
> On 2015/07/02 12:36:04, Dan Eble wrote:
> > I haven't yet reached an understanding of what should be done about
> > make-non-relative-music.
> 
> After some testing, I understand that make-non-relative-music should have been
> used within \autochange.  I've posted a patch in
> https://codereview.appspot.com/250170043/ .  Thanks for finding that defect,
> Thomas.

Too much honor. I only observed an unused variable.

Because I don't know C++ I can't review this part of the patch.
The remarks about license etc should be inserted now or I'll do it with the
proposed follow up to issue 4465.

Otherwise LGTM

[Dan Eble, 2015-07-06 15:36:10]

On 2015/07/03 10:25:52, thomasmorley651 wrote:
> The remarks about license etc should be inserted now or I'll do it with the
> proposed follow up to issue 4465.
> 
> Otherwise LGTM

I left the license commenting for you, as you have offered.  I'm trying not to
spend my time on autochange-related tasks that are nothing more than cleanup,
but rather on bugs or tasks directly related to my partcombine plans.