Re: layout.cc: do not draw empty boxes (issue 6450113)

[joeneeman]

On 2012/09/03 08:16:27, dak wrote:
> http://codereview.appspot.com/6450113/diff/10001/lily/lookup.cc
> File lily/lookup.cc (right):


http://codereview.appspot.com/6450113/diff/10001/lily/lookup.cc#newcode172
> lily/lookup.cc:172: if (b.x ().length () < blotdiameter)
> On 2012/09/03 07:25:53, Keith wrote:
> > It is arguably valid to request a box running from right to left,
for which
> > length() returns zero.  In this application, the Interval class
abstraction is
> > not helping us.  We could defeat the abstraction with
> >  if ( abs( b.x().delta() ) < blotdiameter)
> >     blotdiameter = abs( b.x().delta() );

> Well, "arguably valid" does not mean that we can let some of our code
argue one
> way, some of our code the other.

> If we argue it is invalid, we should deliver a programming error here
in order
> to make people fix the callers.  If we argue it is valid, the code
needs to be
> able to deal with it.

I argue that it is invalid. If you interpret a "right-to-left box" as
being non-empty, then the implementation of Box needs to be rewritten,
since functions such as add_point and widen don't act as expected.

http://codereview.appspot.com/6450113/