Re: Issue 5771: simplify \partial (issue 557440043 by address@hidden)

[dak]

On 2020/02/17 19:17:04, Dan Eble wrote:
> On 2020/02/17 18:41:58, dak wrote:
> > Are you sure this is actually a working idea?  At the beginning of
music,
> Score
> > does not exist and 'Timing is only (reliably?) established as an
alias by the
> > Timing_translator.  For polyrhythmic pieces, the Timing context
alias is moved
> > down the hierarchy along with the Timing_translator.
> 
> What I'm sure of is that the stated scenario for using
descend-to-context here
> was "the Timing_translator is moved," that
> input/regression/partial-polymetric.ly moves the Timing_translator,
and this
> patch did not make any change in the regression tests.  I won't claim
that there
> is full coverage because I didn't investigate that thoroughly.
> 
> About the alias: I see this in the Score definition in
ly/engraver-init.ly:
> 
>   \alias "Timing"
> 
>   %% An alias for Timing is established by the Timing_translator in
>   %% whatever context it is initialized, and the timing variables are
>   %% then copied from wherever Timing had been previously established.
>   %% The alias at Score level provides a target for initializing
>   %% Timing variables in layout definitions before any
>   %% Timing_translator has been run.
> 
> The only state in which (descend-to-context ... 'Score) should have an
effect is
> when the current context is Global.  In any other state, it should
change
> nothing.  And if the current context is Global, (context-spec-music
... 'Timing)
> should find-or-create the Score because of the alias; descending to
Score first
> should not be necessary.

Well, with a bit of juggling around things I have not been able to
trigger a difference.  I am a bit skeptical that that means nobody else
can: we have inventive users and the startup of Timing has been one area
where combinations of things like \skip, \partial and \time have managed
to create crashes.  Since we have various other context-related changes
slated in 2.21.0, this is one of the cases where I'd likely be happier
if the final push had this change end up in 2.21.1.

https://codereview.appspot.com/557440043/