Re: Sending around contexts

[Kieren MacMillan]

Hi Lukas (and Aaron),

> Wow.

Agreed.

> That's what you might call elegant (and I have to admit that this is the 
> first time I hear about dispatchers).

+1 x 2 (which, ironically, still equals 1…)

> But as I imagine Kieren is going to want to use this a LOT :-)

YOU DON’T KNOW ME!!! ;)
Yeah… this will end up getting overused in my code.

> %%%%
> \version "2.22.0"
> 
> newChannel =
> #(define-scheme-function () () (ly:make-dispatcher))
> 
> receiveFromChannel =
> #(define-music-function (chan) (ly:dispatcher?)
>    #{
>      \applyContext
>      #(lambda (ctxt)
>         (ly:connect-dispatchers
>          (ly:context-event-source ctxt)
>          chan))
>    #})
> 
> sendToChannel =
> #(define-music-function (chan event-type) (ly:dispatcher? symbol?)
>   (define (event-proc ev)
>    (ly:broadcast chan (ly:event-deep-copy ev)))
>   (define (context-proc ctxt)
>    (ly:add-listener event-proc (ly:context-events-below ctxt) event-type))
>   #{ \applyContext #context-proc #})
> 
> piano_upper = {
>   c'4\p d' e' f'
>   g'1\mp
>   g'4\f f' e' d'
>   c'1
> }
> 
> piano_upper_II = {
>   c'4\ff\< d' e' f'
>   g'1\ffff
>   g'4 f' e' d'
>   c'1
> }
> 
> piano_lower = {
>   \clef bass
>   c1
>   g,1
>   g,1
>   c1\ff
> }
> 
> myChannel = \newChannel
> myOtherChannel = \newChannel
> 
> \score {
>   <<
>     \new PianoStaff <<
>       \new Staff \with {
>         \sendToChannel \myChannel dynamic-event
>         \omit DynamicText
>       } \piano_upper
>       \new Dynamics \with { \receiveFromChannel \myChannel } { 
> #(skip-of-length piano_upper) }
>       \new Staff \with {
>         \sendToChannel \myChannel dynamic-event
>         \omit DynamicText
>       } \piano_lower
>     >>
>     \new PianoStaff <<
>       \new Staff \with {
>         \sendToChannel \myOtherChannel dynamic-event
>         \sendToChannel \myOtherChannel span-dynamic-event
>         \omit DynamicText
>         \omit Hairpin
>       } \piano_upper_II
>       \new Dynamics \with { \receiveFromChannel \myOtherChannel } { 
> #(skip-of-length piano_upper) }
>       \new Staff \with {
>         \receiveFromChannel \myOtherChannel
>       } \piano_lower
>     >>
>   >>
> }
> %%%%

Oh! Nice. This is really becoming a cool mechanism. Can’t wait to take it out 
for a real spin.

Thanks all!
Kieren.
________________________________

Kieren MacMillan, composer (he/him/his)
‣ website: www.kierenmacmillan.info
‣ email: kieren@kierenmacmillan.info