Re: [GLISS] why the hell all this fuss

[Janek Warchoł]

It's getting better!  yay!

On Fri, Sep 7, 2012 at 11:10 AM, David Kastrup <address@hidden> wrote:
>
> Janek Warchoł <address@hidden> writes:
>> However, i see two problems with this function, and i suppose they're
>> not easy to fix within current framework:
>> 1) it is "prefix".  I'm pretty sure that users will get confused as to
>> why sometimes you write \p after a note, and sometimes before it.
>
> The main reason is that it is _attached_ to the note, like accents are.
> The attachment for dynamics is rather loose: basically it just plays at
> the same time in the Voice.  This attachment is no longer valid when
> time-shifting.  One could doubt the wisdom of turning commands like
> dynamics into post events in the first place: things that make also
> sense time-shifted might be conceptually better represented as
> standalone events.

Maybe.

> Coming back to your proposal: It would be possible to create an empty
> post-event wrapper that can actually contain timed music, thus writing
> something like
>
> \new Voice {
>   c'1
>   \at 1*1/3 \p
>   \at 1*2/3 \<
>   \at 1\!
> }
>
> and have \at as an event function.  I doubt we would be doing people a
> favor, though.  It turns out that \at can actually time-shift arbitrary
> music if you just replace the ly:event? tag with ly:music?

You mean something like this?

at =
#(define-music-function (parser location t e m)
   (ly:duration? ly:music? ly:music?)
  #{ << #m { \skip $t <>$e } >> #})

<<
  \new Staff { \at 2 { e'8 f' g' a' } c'1 }
  \new Staff { c'4 d' e' f' }
>>

Wow! it's cool!

> This makes sense in a number of cases but would
> really get strained if you had to do it in postevent syntax.  In
> particular if you don't want to attach it just to a single note but
> rather a sequence, which would make sense for dynamics.

Like this?

\paper { ragged-right = ##f }

at =
#(define-music-function (parser location t e m)
   (ly:duration? ly:event? ly:music?)
  #{ << #m { \skip $t <>$e } >> #})

\new Voice {
  \at 4. \< \at 2 \! { c'4 d' e' }
}

(hey, that's really cool!)

Frankly, i'd find it more natural to write it postfix:
  { c'4 d' e' } \at 4. \< \at 2 \!
because if follows LilyPond spirit - "notes first, decorations later".
(if that's what you're talking about).

>> (of course if you understand what the function actually does,
>> everything becomes clear - but i think it's important to have syntax
>> that looks consistent and intuitive without reading function
>> definitions (is the word "transparency" appropriate here?))
>
> The problem is to avoid syntax that reads a bit more "intuitive" for
> some use cases and gets totally intractable for others.

agreed.

>> I intended to write this:
>>   { b2 \<@0.5 a2 address@hidden } meaning { << { b2 a2 } {  s4 s2 \< s4 \! } 
>> >> }
>> (i don't insist on having decimal numbers.  It's just that the idea
>> was not to specify a delay duration, but a percent of the "parent"
>> note duration, and decimal numbers look better for this)
>
> Decimal numbers are "inexact".  With computers, you'll find that 0.5 and
> 0.5 will likely add up to result in 1.0, but you'll be lucky if 0.4 and
> 0.6 add up to 1.0.  For music, the concept of simultaneousness is
> sometimes important: if a dynamic change happens one microsecond after
> the attack of a note, it is too late to affect the attack itself.  This
> will significantly change the MIDI and, if done judiciously, also the
> print (where losing the direct attachment to a note may cause quite
> different alignments).

ok, scrap decimals then.