Re: Slur with left and/or right arrow head

[Lukas-Fabian Moser]

Hi Harm,

> Well, it's a little cheating involved :)
> LilyPond does checks for grob-properties, you can't write
> \override Grob.self-invited-property = ...
> without "explaining" this `self-invited-property´ to LilyPond.
>
> But details and bound-details are established properties taking alists
> containing key-value-pairs of subproperties.
> Adding a new one like `arrow-left´ will not disturb other procedures
> reading `(bound-)details´, they simply don't look for the new ones
> (ofcourse you need to care not to take a preserved one). There is no
> checking of subproperties.
> So I code frequently this way.
Thanks for the explanation!
> I believe bound-details is more common for grobs with the
> line-spanner-interface, but it makes no real difference, afaik.
>
> I'm aware doing
> arrow-left -> LEFT
> arrow-right -> RIGHT
> is not that elegant, but thee are two names needed with three options
> LEFT/RIGHT/#f
> I'll have to think over it.

But why not just a true/false flag?

arrow-left -> ##f (default) / ##t
arrow-right -> ##f (default) / ##t

At the moment, arrow-left = #RIGHT does something that might even be 
turned into a useful arrow-tail, but that's not yet the case, and for 
now, I think, "no tip / arrow tip" are the reasonable alternatives.

By the way, does the [bound-]details construct allow for nested 
sub-properties? I ask because of the Glissando analogy where it's 
.bound-details.left.arrow = ##f / ##t.

Lukas