Re: 2.21 note definition change

[David Kastrup]

Paul Scott <waterhorse@ultrasw.com> writes:

> On 6/23/20 2:23 PM, David Kastrup wrote:
>> Paul Scott <waterhorse@ultrasw.com> writes:
>>
>>> The 1st argument for note is now a duration rather than a string.
>>>
>>> I had some scheme definitions which were variations on \tempo.
>>>
>>> I used (string?) for this value before.  What is the new scheme
>>> equivalent?  (duration?)
>> ly:duration?
>
> Thank you, David.
>
> I believe I had tried that.
>
> Here's my MWE which hopefully will show someone what dumb mistake I'm
> making:
>
> \version "2.21.2"
>
> #(define-markup-command (notetest layout props dur) (ly:duration?)
>   interpret-markup layout props
>   (markup
>    #:note dur #up
>  ))
>
> {
>   \tempo \markup{ Allegro \notetest #4 }
>   c'1
> }
>
> Thank you,

Several.  Is there a reason you use the markup macro rather than
#{ \markup ... #} ?  The latter can do the same but is more
straightforward to use when not familiar with Scheme syntax, and you
really make it appear like you aren't.

You write interpret-markup ... instead of (interpret-markup ...) .  In
Scheme, every pair of paren conveys meaning.  They aren't syntactic
sugar which you can add or remove.

Then you write #up in Scheme.  # in Scheme introduces specially parsed
expressions, such as #(...) for literal vectors, or #{ ... #} for
embedded LilyPond or #t or #f for true and false boolean literals.

And both LilyPond and (Guile) Scheme are case sensitive: you cannot swap
up and UP.

In LilyPond expressions, you'd write #UP here, with # escaping from
LilyPond mode into Scheme mode, and UP being the Scheme expression in
question.  If you are doing copy-and-paste from documentation, only
LilyPond mode will work sensibly, so my recommendation of using
#{ \markup ... #} here.

Then you call \notetest #4 where 4 is a number, not a duration.  To get
into LilyPond parsing mode for an argument of a markup function, one can
use braces (I am not sure this feature will persist to 2.22 in this
form, but 2.21 is a development version).  So you need to write { 4 }
here in order to get a duration.  In a way, that is syntactic sugar for
writing ##{ 4 #} but the latter looks uglier.

-- 
David Kastrup