Re: A work-in-progress guide to extending LilyPond

[Jean Abou Samra]

Le 10/04/2021 à 19:16, Thomas Morley a écrit :

> Am Sa., 10. Apr. 2021 um 17:55 Uhr schrieb Thomas Morley
> <thomasmorley65@gmail.com>:
> > I'll  check for your recent changes soon.
> Apart from a nit (below) all looks great now.
>
> You did not extend section "Introduction to extending - Printing
> values" with other printing procedures.
> Mentioned are `display' and `write' from scheme and `ly:message'. In a
> later section `displayMusic' and `display-scheme-music'.

Okay, I forgot about this one. I added
some text about (ice-9 format) (not
pretty-print, see below).


> Nowadays it's very rare I use `display', `write' or `ly:message',
> because all of them don't print (a)lists in a readable structered
> format, although my codings always proceed with lots and lots of
> printed data.
> I nearly always use `pretty-print' and for music-expressions
> `display-scheme-music'
>
> I'd like to suggest to mention `pretty-print', at least for printing lists. See:
> {
>    \override Slur.after-line-breaking =
>      #(lambda (grob)
>        (let ((cps (ly:grob-property grob 'control-points)))
>          (display-scheme-music cps)
>          (pretty-print cps)
>          (ly:message "~a" cps)
>          ))
>    b'1( b'')
> }
> ->
> (list (cons 0.732364943841144 1.195004)
>        (cons 1.76258769418946 3.05939544438528)
>        (cons 6.83883925432087 5.14594080151585)
>        (cons 8.88241194297576 4.545004))
>
> ((0.732364943841144 . 1.195004)
>   (1.76258769418946 . 3.05939544438528)
>   (6.83883925432087 . 5.14594080151585)
>   (8.88241194297576 . 4.545004))
>
> ((0.732364943841144 . 1.195004) (1.76258769418946 . 3.05939544438528)
> (6.83883925432087 . 5.14594080151585) (8.88241194297576 . 4.545004))
>
> A pity that ly:message does not accept the ~y-formatter.

Now go review https://gitlab.com/lilypond/lilypond/-/merge_requests/721. ;-)


> So far the link to the guile manual about format-options may lead wrongly.
> Btw, you link to guile-3.0.5 ...

Indeed, thanks for spotting. Fixed now.

Best regards,
Jean