Re: (scheme-)engraver in 2.20/21

[Aaron Hill]

On 2020-09-24 2:51 am, Jan-Peter Voigt wrote:
> Hi all,
>
> after some other very involving projects I can now refocus on lilypond 
> :-)
>
> I probably missed a change in 2.20/21. If I create a scheme-engraver 
> the
> "start-translation-timestep" slot is not called, if the "initialize"
> slot has been called in this particular timestep. If this the intended
> behaviour I appreciate it because it is consistent. The "start-trans.."
> slot wasn't called before for instant voices, but for regular installed
> contexts. So now I have to finish "initialize" of the engraver with
> "start-trans..." in any case.
>
> So my question is if this is intended and not likely to change?
> Sorry, if I missed discussion about this!
>
> I have a demo below, where you can see that "start-trans..." is not
> called, if "initialize" has been called before in the same timestep.

It would seem that initialize/finalize are primarily concerned with the 
lifetime of the context whereas (start|stop)-translation-timestep deal 
with moving from one moment to the next in music.  As such I do not see 
these things as related, so what would be the reason for initialize to 
trump start-translation-timestep?

I am curious more about the statement that start-translation-timestep 
was not "called before for instant voices, but for regular installed 
contexts".  Do you have a MWE that demonstrates this behavior?  Running 
the code you already provided against 2.18.2 and 2.19.55 (both via 
lilybin.com), and 2.20.0 locally show the call to 
start-translation-timestep after initialize for all three contexts.


-- Aaron Hill