Fixes issue 1881 (cyclic dependency with beam calculations)

Fixes issue 1881 (cyclic dependency with beam calculations)

[MikeSol, 2011-09-17 07:53:50]

Hey all,

A one-line-deletion patch to fix 1881.

I think the re-introduction of length and stem-begin-position both made this
line obsolete and triggered cyclic dependencies.

I'm still not sure why these dependencies resulted in changed visual output, but
this patch seems to fix the cyclic dependency error without causing any change
in the regtests.

Cheers,
MS

[Neil Puttock, 2011-09-17 09:07:59]

LGTM.

BTW, I have a few queries about stem::length:

  76   (let* ((d (ly:grob-property grob 'direction))

You don't use 'direction; is it still necessary to get it to trigger other
calculations?

  79          (beam (ly:grob-object grob 'beam)))

Why do you need to access 'beam?  AFAICT, the callback will never be triggered
on beamed notes, so it's redundant.  It also makes the last line look like a
thinko:

  82         (ly:grob-property grob 'length))))

This would be a calculation-in-progress, since you're already inside the
callback.

[mike_apollinemike.com, 2011-09-17 09:28:04]

On Sep 17, 2011, at 11:07 AM, n.puttock@gmail.com wrote:

> LGTM.
> 
> BTW, I have a few queries about stem::length:
> 
> 76   (let* ((d (ly:grob-property grob 'direction))
> 
> You don't use 'direction; is it still necessary to get it to trigger
> other calculations?
> 

I doubt it - it's likely vestigial.  I'll work on a patch that addresses the
issues below and remove this line.

> 79          (beam (ly:grob-object grob 'beam)))
> 
> Why do you need to access 'beam?  AFAICT, the callback will never be
> triggered on beamed notes, so it's redundant.  It also makes the last
> line look like a thinko:
> 
> 82         (ly:grob-property grob 'length))))
> 
> This would be a calculation-in-progress, since you're already inside the
> callback.
> 

Agreed - I can likely get rid of all this stuff.  I like the term `thinko' :)

I'll try reducing this as much as possible and will post a patch.

Cheers,
MS