Re: Avoid repeats of 'staff-affinity' warning; change text. (issue4278058)

[Keith OHara]

On Mon, 21 Mar 2011 23:06:12 -0700, Joe Neeman <address@hidden> wrote:

> > Unfortunately, if I protect the assignment to the property with an  if
> > (!pure), I am letting the page-breaking planning rely on the user-requested
> > affinities, and then changing them for the page-layout phase.  The boolean
> > 'pure' asks explicitly that we keep the state unchanged, but there was
> > always an implicit expectation that certain properties are unchanging.
>
>
> I don't quite understand this comment. The only effect of set_property is to
> prevent the warning from being triggered more than once per system. In fact,
> the layout would be completely unchanged even if you removed the whole
> if(after_affinity > before_affinity) block. So why does it matter if we
> condition set_property on something?
In a typical case, the effect is  after->set_property("staff-affinity", DOWN)
and then when get_spacing_spec is called to determine the next spring, working 
through the (non)staffs in the system, it will look up the staff affinity we just 
set for use as before_affinity, thus the next spring is changed.  The code in the 
if(after_affinity>before_affinity) block does change the output for the example 
at the head of issue 1555.