Re: Let \time in mid-measure work without warning in some cases (issue 143450043 by address@hidden)

[David Kastrup]

address@hidden writes:

> On 2014/09/23 14:17:11, dak wrote:
>> So I propose we junk the warning if we cannot place it accurately:
> people who
>> want whole-measure warnings are supposed to use barchecks anyway.
>
> If the only issue were wholeness of measures, I would agree; however, if
> there are other problems such as incorrect bar numbers, it would be nice
> to have a warning, because that is not going to be caught by a common
> bar check.  Do you agree?

_Are_ incorrect bar numbers a problem?  When do we get them?

>> I think "\time will start a new measure, follow it with \partial if
>> you don't want that" is a clear rule and probably not all that
>> different from what people would be expect/write without reading the
>> manual previously.
>
> If the user wanted to start a new measure, why was the first measure
> left incomplete?

Because the meter change, including the respective accents to be placed
in the measure occurs before the measure is complete.  If it didn't, the
meter change would have been written at the end of the measure.

Since the metric change is _before_ the previous meter has completed, it
is an arbitrary musical decision how much material of the new meter may
count as \partial.  I don't see your particular case as the gold
standard of when not to warn.  At the same time, I can understand that
you want some way _not_ to get a warning.  A perfectly reasonable way to
do that is to _require_ a \partial after \time in case a
non-whole-measure is desired.  Since \partial these days does its work
at a very late time and we don't really have a hook for the time "after
any \partial might have done its work", I don't see a good way to _get_
that warning or rather how _not_ to get that warning _iff_ there is no
\partial at all.

> Setting measurePosition to 0 on \time doesn't work.

\partial does something different.

> If you want to require \partial for my use cases, what works is to set
> measurePosition to the length of the new measure.

I do want to require \partial for your use cases even though I can think
of no good way to trigger a warning when it is left off in case of an
incomplete measure before.  The resulting behavior of cutting the
previous measure short when no \partial is given _would_ warrant a
warning.  I just don't see how to do that.

> That becomes a problem if the user really wants to start a new measure
> (which doesn't make sense); omitting \partial is not good enough
> because no bar line is engraved unless the user writes \bar
> explicitly, and then if a parenthesized bar number is engraved, it is
> wrong.  Setting the position to a useless default is rather
> dissatisfying compared to finishing the measure by default.
>
> Your comment about grace notes went over my head, but it is not
> forgotten, and I will think about it when I have more time.

> https://codereview.appspot.com/143450043/

I'm currently still working on GUILE2 stuff.  Once I'm more or less
through, I'll try proposing something akin to what I described and check
how it works with your regression tests.

-- 
David Kastrup