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

[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.

> 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?

-- 
David Kastrup