Re: bar-line interface part 2/2: New bar line definition standard (issue 6498052)

[Marc Hohl]

Am 05.10.2012 21:42, schrieb Thomas Morley:
> 2012/10/5  <address@hidden>:
> > Marc wrote:
> > > (define-bar-line ...) or \defineBarLine allows for new
> > > definitions. These functions have four arguments,
> > > namely the bar line itself, the bar line used at the end
> > > of line, the bar line used at the begin of a new line
> > > and the span bar line.
> >
> > It just occured to me: is there any way to specify different span bar
> > lines (at the end of the line and at the beginning of the line)?
> >
> > Janek
> Marc and me, we discussed this some time ago and decided not to
> provide that functionality.
IIRC, I was the one which *proposed* the idea of having different
span bars but decided to continue with one span bar per bar line
only, because I treid to adopt the old c++ way in which the span bars
werde defined and handled.

So this was more or less *my* fault.

Thinking a bit more in detail, I think the input format
\define BarLine #'(bar end-of-line begin-of-line) #'(span-bar 
end-of-line begin-of-line)
or alternatively
\define BarLine #'(bar end-of-line begin-of-line) #'(span-bar)
which expands internally to
\define BarLine #'(bar end-of-line begin-of-line) #'(span-bar span-bar 
span-bar)
is indeed the cleanest solution.

With my current approach, Lilypond raises a warning if the corresponding
span bar to [begin|end]-of-line-bar is not defined.
So your proposal is definitively better.

> It would make things more complicated for the user and I think it is a
> rarely needed feature.
This was my first opinion, too, but on the other hand, a cryptic warning and
the need to define one or two additional bar lines to get rid of it is not
user-friedly either.

Regards,

Marc