On 2019-11-17 3:10 pm, Aaron Hill wrote:
On 2019-11-17 12:38 pm, Paolo Prete wrote:
Hello,
is it possible to revert a tempo change to the previous tempo setting,
without explicitly writing this previous one?
Something like (pseudo-code):
\tempo 4 = 120 { ...some music .... } \temporaryTempo 4 = 160 { ...
some other music .... } \unset \temporaryTempo
Not sure if this is really the right way to do things:
Here's a version that is a little safer about unsetting the property as
well as emitting a warning when the stack is empty:
%%%%
\version "2.19.83"
#(define tempoStack '())
pushTempo = #(define-music-function () ()
(define (pushTempoHelper ctx)
(let ((tempo (ly:context-property ctx 'tempoWholesPerMinute #f)))
(set! tempoStack (cons tempo tempoStack))))
#{ \context Score \applyContext $pushTempoHelper #})
popTempo = #(define-music-function () ()
(define (popTempoHelper ctx)
(if (null? tempoStack)
(ly:warning "Unable to pop a tempo. Did you forget to
\\pushTempo?")
(let ((tempo (car tempoStack)))
(set! tempoStack (cdr tempoStack))
(if tempo
(ly:context-set-property! ctx 'tempoWholesPerMinute tempo)
(ly:context-unset-property ctx 'tempoWholesPerMinute)))))
#{ \context Score \applyContext $popTempoHelper #})
\score {
{
\markLengthOn
\tempo "I. Default"
{ b'4 4 4 4 } \bar "||"
\pushTempo \tempo "II. Andante" 4=90
{ b'4 4 4 4 } \bar "||"
\pushTempo \tempo "III. Allegro" 4=140
{ b'4 4 4 4 } \bar "||"
\popTempo \tempo "Tempo II"
{ b'4 4 4 4 } \bar "||"
\popTempo \tempo "Tempo I"
{ b'4 4 4 4 } \bar "||"
\popTempo \tempo "Tempo 0?!"
{ b'4 4 4 4 } \bar "|."
}
\layout {} \midi {}
}
%%%%
NOTE: The snippet above intentionally causes a warning to appear.
-- Aaron Hill