Re: Create Score context before starting iteration. (issue 44860045)

[Devon Schudy]

David Kastrup wrote:
> https://codereview.appspot.com/44860045/diff/60001/input/regression/initial-contexts.ly#newcode10
> input/regression/initial-contexts.ly:10: %%and iteration can't skip time
> without it.
> This comment is a bit of a non-sequitur: time is kept in the Global
> context, so it could get skipped.

Hmm, \skip successfully skips time, but doesn't update
measurePosition, because Timing_translator doesn't exist yet, so the
barlines are in the wrong places.

>  I am not actually sure how SkipEvent even works.

Apparently it (and SkipMusic) just works by having a nonzero length.

> https://codereview.appspot.com/44860045/diff/60001/lily/global-context.cc#newcode148
> lily/global-context.cc:148: find_create_context (default_child_, "",
> SCM_EOL);
> This precludes \new Score \with ..., quite a no-no.

\new Score creates the context in construct_children, so that still
works. Something like { \skip 4 \new Score ... } would fail, though.
Should that work?

[on calling start_translation_timestep for new translators]
> Isn't that sufficient to have the Score context created in time?
> Without requiring the other fixes?

It doesn't create it in time, but it does start the Score translators
properly when they're created late — but it still doesn't start
Score_performer correctly, because it's a Translator_group, not a
translator. However, the only Translator_group per_timestep
initialization is creating Score_performer::audio_column_, so if
Audio_column goes away, there's nothing left to do there.