Re: \once \revert

[Janek Warchoł]

2011/8/19 Carl Sorensen <address@hidden>:
> On 8/19/11 10:15 AM, "David Kastrup" <address@hidden> wrote:
>>
>> Up to now, \once \revert is not really documented nor used.  I have not
>> yet dug through the existing code in order to figure out what it does if
>> anything (most likely ignoring \once, but not sure).
>
> I would expect that \once \revert would revert an \override for the current
> time step only (meaning events whose start time is the current moment).  For
> any events whose start time is other than the current moment, the \override
> would continue to apply.

+1

>> In order to not have the override/revert stack get into unexpected
>> interactions, I want to change \once\override to be impervious to normal
>> reverts.
>
> This seems to me to be a wise decision.  \once \override is a statement that
> you are creating an override for everything happening at the current moment;
> reverts would not seem to apply.

+1

>> That would mean that \once\revert is an obvious candidate for reverting
>> a \once\override before its time.  However, I have no idea whether there
>> is an actual sensible use for that functionality.
>
> I can see no sensible use for that functionality.  You would have
> conflicting statements about what should happen at this time.

+1

>> \once\revert could also mean to let a current non-once override become
>> inactive just for the current time step.
>
> As I mentioned above, I think this is the logically consistent meaning.

+1

>> IF one wanted to get crazy, one could use \once\revert for one of the
>> two things, and \revert\once for the other.  Which one for which, and
>> would anybody remember that?
>
> I agree that this would be crazy.   But if we were going to do it, \once
> \revert should revert an \override, but only for the current moment, and
> \revert \once should revert a \once \override, IMO.  But I would not be in
> favor of this proposal.

+1

> In fact, I think I would be in favor of removing \once \revert from the
> parser.  The semantics of \once \revert can be confusing, and the same
> behavior could be achieved with a \once \override.  But I would be open to
> arguments from those who see good uses of \once \revert.

+0.5, i'm not sure.

I see that there is more advanced discussion going on, but i cannot
dive into it now.  Maybe later.

cheers,
Janek