Avoids direction checking for cross-staff side-support-elements

Avoids direction checking for cross-staff side-support-elements

Only uses direction if it is not a callback. Otherwise, the callback
may lead to cyclic dependencies.

[MikeSol, 2013-04-21 20:03:32]

Removes unnecessary direction check

[MikeSol, 2013-04-21 20:06:08]

Removes unnecessary check of direction

[Keith, 2013-04-23 22:06:27]

lgtm

Somewhere I'll have to write down the definition 
"cross-staff": true for a grob whose placement or size could depend on the
spacing of staves on the page.

https://codereview.appspot.com/8557044/diff/6001/lily/side-position-interface.cc
File lily/side-position-interface.cc (right):

https://codereview.appspot.com/8557044/diff/6001/lily/side-position-interface...
lily/side-position-interface.cc:160: // we avoid the circular dependency by
returning true
/* If 'me' is placed relative to any cross-staff element with a 'direction
callback defined, the placement of 'me' is likely to depend on staff-spacing,
thus 'me' should be considered 'cross-staff' */

https://codereview.appspot.com/8557044/diff/6001/lily/side-position-interface...
lily/side-position-interface.cc:169: // as cross-staff. otherwise we do.
if you do not use the vaguest possible words 'element' (for the variable 'me')
and 'grob' (for 'elts[i]') and refrain from using 'aligning' to mean 'aligned'
then we might not find this comment impossible to understand.  otherwise we do.

[MikeSol, 2013-04-24 04:52:53]

Good times with comments.

[mike7, 2013-04-24 05:05:34]

On 24 avr. 2013, at 01:06, k-ohara5a5a@oco.net wrote:

> lgtm
> 
> Somewhere I'll have to write down the definition
> "cross-staff": true for a grob whose placement or size could depend on
> the spacing of staves on the page.

It's not quite that.  In the definition above, a treble clef on the 5th staff of
a system is cross-staff because its placement depends on what is contained in
the systems above.  What will not change is its placement with respect to its
staff.  I like "Any grob that is not the element of a vertical axis group or
whose relative extent with respect to the vertical axis group of which it is an
element changes as a result of how far apart two or more vertical axis groups
are." This opens up the definition to all vertical axis groups (i.e. Dynamics,
ChordNames). But it is obviously too technical for a docstring.

Cheers,
MS

[wl_gnu.org, 2013-04-24 07:22:51]

> I like "Any grob that is not the element of a vertical axis group or
> whose relative extent with respect to the vertical axis group of
> which it is an element changes as a result of how far apart two or
> more vertical axis groups are."

If you are able to `convert' this to a bunch of simpler sentences
together with one or more examples, this will certainly work.


     Werner