On 11 May 2018 at 17:58, Aaron Hill <lilyp...@hillvisions.com> wrote:
> On 2018-05-11 08:46, David Kastrup wrote:
>
>> Aaron Hill <lilyp...@hillvisions.com> writes:
>>
>> On 2018-05-11 06:53, Gianmaria Lari wrote:
>>>
>>>> Sorry to bother with a simple question. Why this does not work?
>>>>
>>>> \version "2.19.81"
>>>> pit = #(define-music-function
>>>> (p) (ly:pitch?)
>>>> )
>>>> { \pit c' }
>>>>
>>>
>>> The result is "error: music function cannot return c'". It appears
>>> that a simple pitch by itself is not enough to qualify as music.
>>>
>>
>> #{ $p #}
>> It's desirable to be able to enter pitches as #{ c' #} and similar. Add
>> a duration to get a music expression.
>>
>
> But can you return an incomplete music expression? It seems like that is
> the underlying issue why the original code does not work.
>
> If you change the function to "#{ { $p } #}", it compiles.
>>>
>>
>> Yes, but the duration is not really well-defined here (happens to end up
>> as the default duration of the current parser).
>>
>
> True, I was not advocating that this is a useful construct, merely showing
> that it results in a minimally valid expression.
>
yes, I was thinking that the problem was related to the fact that #{ $p #}
could be "considered" an incomplete music expression. But the fact that the
following code
#{ $p $p #}
and
#{ { $p } #}
compiles, make me think that there were something more....
Anyway, should I avoid to write something without duration even if it
compiles? For example, should I avoid the following?
#{ c $p c #}
I considered this useful. Because the function return something with a
duration that depends from the previous music and this can be 'practical'...
g.
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