Re: Issue 3918: Add \alternatingTimeSignatures (issue 97110045)

[David Kastrup]

Paul Morris <address@hidden> writes:

> Thomas Morley-2 wrote
>> Maybe a step in this direction:
>> 
>> \version "2.19.6"
>> 
>> appear =
>> #(define-music-function (parser location mrkp item)
>>    (markup? symbol-list-or-music?)
>>    (let ((stil (lambda (item)
>>                  (grob-interpret-markup item mrkp))))
>>      #{ \tweak stencil #stil #item #}))
>
> Assuming we would want to support stencils as well as markups, we'd need a
> new type predicate: 
>
> markup-or-stencil?
>
> And if it is to be as flexible as a \tweak, then it should also support
> procedures (i.e. that return a stencil).

I don't think it makes a lot of sense to support procedures as then so
many internals shine through that the abstraction is basically gone.
I am already unconvinced about stencils for that reason.

> So we'd need:
>
> markup-or-stencil-or-procedure?

markup-or-stencil-or-procedure-or-false? ...

We don't do this elsewhere.

-- 
David Kastrup