Re: Syntactical question [was: Re: Call for help with bar lines]

[Marc Hohl]

Am 27.09.2012 09:10, schrieb David Kastrup:
> Marc Hohl <address@hidden> writes:
>
> > Am 26.09.2012 14:45, schrieb Thomas Morley:
> > > [...]
> > > Hi Marc,
> > >
> > > an idea, don't know if it's really helpful:
> > >
> > > >From 2.16.0-bar-line.scm, bar-glyph-alist:
> > > The old definition of  bar "empty" was: ("empty" . (() . ()))
> > > The old definition of  bar "" was: ("" . ("" . ""))
> > With regard to that, I have to make a distinction between
> > "" and '() in the new bar line interface.
> >
> > What do you think would be better: using a symbol instead of '(),
> > so one can write
> >
> > \defineBarLine "|" "|" 'none "|"
> >
> > or using #f instead:
> >
> > \defineBarLine "|" "|" #f "|"
> I think I'd actually prefer
>
> \defineBarLine "|" #'("|" #f "|")
>
> or
>
> \defineBarLine "|" ##("|" #f "|")
>
> to bring some structure into what is being defined in terms of what.
Just to clarify: the arguments are

\defineBarLine <bar line> <bar-line-at-end-of-line> 
<bar-line-at-begin-of-next-line> <span-bar-line>

But some kind of grouping *does* make sense.
> > or finally defining an "empty stencil" glyph:
> >
> > \defineBarLine "|" "|" "x" "|"
> >
> > (note that "" is not the same as "x", as Harm explained; "" draws a
> > stencil with
> > zero width, "X" would draw *no* stencil at all).
> What do we need a zero width stencil for?
\bar "" inserts an empty stencil, so the padding around the
(invisible) bar line is preserved. If there's no stencil, there will
be no padding.

Marc
>