2009/4/11 Mark Polesky <markpole...@yahoo.com>:
>
> Neil Puttock wrote:
>> > Why does Slur have an 'avoid-slur property?
>> So they avoid phrasing slurs.
>>
>> \relative c' {
>> \override Slur #'avoid-slur = #'outside
>> c\( d( e) f\)
>> }
>
> Okay, but the semantics are contradictory. One could think
> of the command in your example in two different ways:
> Adjust the slur to keep the slur outside the phrasing-slur.
> -or-
> Adjust the slur to keep the phrasing-slur inside the slur.
You can see why avoid-slur is accompanied by `ugh'. ;)
It's the former meaning; you have to imagine avoid-slur actually means
avoid-(phrasing-)slur.
> Neither is reflected with the current syntax. Either of
> these (non-functioning) commands would be clearer:
> \override Slur #'avoid-phrasing-slur = #'outside
Adding avoid-phrasing-slur would mean duplicating all the slur
avoidance code just for the sake of a different name.
> \override PhrasingSlur #'avoid-slur = #'inside
No. The acknowledged object (Slur) does the avoidance. Since it's
fair to assume that phrasing slurs always encompass slurs, there's no
reason for the Slur_engraver to acknowledge phrasing slurs.
> As a kludge, we could add an exception clause to the
> docstring, but ideally that's the wrong solution IMO.
>
> Lastly, this construct is also semantically lacking:
> \override Staff.Clef #'avoid-slurs = ##f
> It's really the slur that's avoiding the clef. This
> would be more intuitive:
> \override Slur #'ignore-clefs = ##t(default would be #f)
> ...but that would be a terrible idea, because you'd want
> 'ignore-time-signatures, 'ignore-key-signatures, etc...
I agree it's not ideal, but it probably arises from the fact that the
avoid-slur infrastructure was already in place when the non-musical
avoidance code was added; I imagine it was much easier to rely on the
existing code to do the avoidance work, rather than implementing an
additional framework just for clefs, time signatures and key
signatures.
> Maybe something like this would be ideal:
> \override Slur #'avoid-list =
> #'(clef key-signature time-signature ...)
> Maybe not exactly that, but something like it? And then
> you could do the same thing for Tie andPhrasingSlur.
That list would get very long if it included the grobs which are
currently acknowledged. :) It would probably only work as a context
property, otherwise you couldn't be sure that avoidance code has
access to the grobs which need avoiding.
>> > 2. add a choice: 'ignore
>> Sounds like a good idea, and only requires one extra
>> line of code...
>
> Don't let me stop you! (:
Why the sad face? I'm waiting for your patch to the IR for 'avoid-slur. :)
>> > 4. implement 'avoid-ties and 'avoid-phrasing-slurs?
>> Judging by the number of `ugh' comments related to
>> avoid-slur in the source, extending the same behaviour
> < to ties is probably undesirable (though it would be
>> good if they avoided clefs and time signatures).
>
> Only if the user could choose.
Oh, definitely; you could imagine the typesetting horrors if the
avoidance were as broken as the current behaviour over line breaks.
Regards,
Neil
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