Re: proposal: second style for quartertone accidentals

[Juergen Reuter]

On Mon, 29 Jan 2007, Han-Wen Nienhuys wrote:

> > . So it seems that the use of "Accidental #'style" is deprecated and one
> > should set the alteration-alist directly. (But changing the style
> > property still works in v2.11.13, even if I don't know why, given that I
> > couldn't find the code handling it). What is the reason for this? To me
> > the former notation seems much more intuitive and easy to use.
>
> The recent microtone improvements needed a much more flexible way to map
> pitches onto symbols, and it seems superfluous to have two mechanisms for
> setting glyphname at the same time.  It would be possible  to have a
> mechanism to set the alist based on the style property, but I thought it
> would be overkill.

Maybe I should re-propose an idea that I posted maybe 5 years ago, but 
which was considered overkill at that time.

Styles could be defined in a cascaded way.  Say, there is an Accidental 
style "default" that just maps the standard non-microtonal accidentals to 
the modern accidental glyphs.  The style should be however undefined for 
microtonal accidentals.  Now, suppose that there is another style 
"arrow-microtonals" that only maps microtonal accidentals to arrow-style 
glyphs, but keeps silent on non-microtonal accidentals.  Then it would be 
nice for the lily user to compose a style by setting a list of such 
predefined styles:  "\override Accidental #'style = #'(arrow-microtonals 
default)".  That is, for each accidental, lily should first search in the 
"arrow-microtonals" mapping if the acciental is mapped to some glyph.  If 
no glyph is defined in this mapping, lily should look at the next mapping 
"default".  That is, you get a combination of standard modern accidentals 
with arrowed microtonals.

There is one downside:  If the style "default" defines only the glyphs for 
non-microtonal accidentals, one always has to explicitly set a microtonal 
style, if microtonals are to be used.  In other ways, the value for the 
style property tends to become a long list.  In order to fix this 
downside, one may also allow a style to "import" further styles.  For 
example, suppose accidental style "standard" implicitly imports 
"non-arrow-microtonals".  That is, if you set "\override Accidental 
#'style = #'(default)", you also implicitly get non-arrow-microtonal 
accidentals, just as if you would have said "\override Accidental #'style 
= #'(default non-arrow-microtonals)".  Note that you still can say 
"\override Accidental #'style = #'(arrow-microtonals default)".  This will 
effectively override the non-arrowed microtonals that are implicit in the 
default style with arrowed microtonals, because the arrowed microtonals 
mapping occurs earlier in the list.

Another downside of this approach could be performance, since each glyph 
lookup would result in iterating through nested scheme lists.  Maybe, a 
sophisticated caching or precomputing approach could alleviate any 
performance issues.

No, unfortunately I have currently no time to work on this :-(.  These are 
just generic thoughts...

Greetings,
Juergen