Urs Liska <li...@openlilylib.org> writes:
> Am 20.06.2018 um 11:38 schrieb David Kastrup:
>
>> #(define-macro (define-my-custom-function . body)
>> `(define-music-function (mus) (ly:music?)
>> (let*
>> ((elts (ly:music-property mus 'elements))
>> (cnt (length elts)))
>> ,@body
>> mus)))
>>
>> That's what one would call a pretty unhygienic macro since it messes
>> with a number of symbols/identifiers not specified by the user.
>
> Hm, valid point. But I think it is worth it given the use case (I will
> experiment and keep your point in mind, though).
By the way, you'll probably arrive at something like
#(define-macro (define-my-custom-function maybe-doc . body)
`(define-music-function (mus) (ly:music?)
,(if (string? maybe-doc) maybe-doc
"define-my-custom-function was here")
(let*
((elts ...
,@(if (string? maybe-doc) body (cons maybe-doc body)))
in order to let the user potentially specify a doc string.
--
David Kastrup
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