Re: Keep a staff alive with multiple layers (issue 308910043 by address@hidden)

[dak]

On 2016/08/21 16:23:57, mark_opus11.net wrote:
> On 2016/08/21 16:22:14, http://mark_opus11.net wrote:
> > Group lower-level contexts

> This introduces a `VerticalAxisGroup.keep-alive-group' property


> which can be set to a symbol to associate a subset of contexts


> under the control of the same Keep_alive_together_engraver.


> This group can further be set to operate only up to a maximum

> layer level with the `keep-alive-group-layer' property.

Well, this doesn't seem to do more than the removal-friends/removal-foes
proposal (or does it?) and complicates things thoroughly.
So let me suggest yet-another-proposal that might require less intricate
planning (and the intricate planning aspect was the thing speaking
against removal-friends/removal-foes and, to be realistic, already
against the currently implemented code which nobody who has a need for
it would seem to actually understand well enough to actually use).

We create a new context, say RemovalGroup.  It has no engravers apart
from the Keep_alive_together_engraver.  And the
Keep_alive_together_engraver does not descend into contexts already
having a Keep_alive_together_engraver, instead letting _that_
Keep_alive_together_engraver make its decisions and, uh, consider itself
alive if any of its subcontexts is alive?  That way its layer number
could be assigned independently from the layer numbers of its
subcontexts, making it possible not to have to keep a global tally of
subgroups but rather use group numbers fresh at each layer.  Which would
greatly facilitate providing context mods for assigning all the layer
numbers and stuff as they would not need to take into account lower or
higher groupings.

This would sound _almost_ as powerful as your plan and considerably
simpler in use.  The downside is that if you wanted to have a group with
non-contiguous elements, you'd have to put them contiguous into the
source and juggle with alignBelowContext and alignAboveContext for
rearranging them.  But is that a common use case?  I hope not, but I
might be overlooking something in the context of lyrics.

https://codereview.appspot.com/308910043/