I didn't know about \default or the dot/comma separated number/symbol
lists! I can see those being useful in some circumstances. I was thinking
about cases where an undefined amount of things different than symbols or
numbers are required, and the closest I can imagine is chaining functions
to create the illusion of a variable amount of arguments, like this:
> \version "2.19.80"
> #(define (end-list? obj)
> (and (list? obj)
> (let ((item (last obj)))
> (and (symbol? item)
> (equal? "end" (symbol->string item))))))
>
> end = #(list 'end)
>
> #(define (el->curated-el el)
> (delete 'end el))
>
> untilEnd =
> #(define-void-function (proc el) (procedure? end-list?)
> (let ((curated-el (el->curated-el el)))
> (for-each
> (lambda (elem)
> (proc elem))
> curated-el)))
>
> selfAppending =
> #(define-scheme-function (e-l) (end-list?)
> (let ((self-input (list (cons 1 2) (cons 3 4))))
> (append self-input e-l)))
>
> selfAppendingInput =
> #(define-scheme-function (input e-l) (scheme? end-list?)
> (append (list input) e-l))
> \relative c'' {
> c d e f
> \untilEnd #pretty-print
> \selfAppending
> \selfAppendingInput #'(some useful input?)
> \selfAppendingInput #selfAppending
> \selfAppending
> \end
> g a b c}
>
> This structure just happens to work for something I'm trying now but I can
see it being too narrow in general.
@Urs, I not familiar with \with blocks, I'll take a look at the oll-core
code and experiment a bit with it. Maybe I'll be able to help.
2018-03-01 4:55 GMT-03:00 David Kastrup <[email protected]>:
> Stefano Troncaro <[email protected]> writes:
>
> > Thank you! I see that this is not an option then. Also, I now understand
> > why I couldn't make the optional arguments work, since I always left them
> > for last.
> >
> > Do you know if it is possible to have a flexible amount of optional
> > arguments that appear before the last mandatory one? Say, for example
> > (define-music-function (arg1 args music) (number? ??? ly:music?) where
> arg1
> > and music are mandatory, and basically everything between arg1 and the
> next
> > music expression is compacted into a list and accessed as args in the
> body
> > of the function. Not with that syntax necessarily, but something that
> > allows for that kind of usage?
>
> You know that a number or symbol list can be entered as a
> comma-separated list?
>
> --
> David Kastrup
>
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