RE: Fret Diagram markup

[Carl D. Sorensen]

> -----Original Message-----
> From: Han-Wen Nienhuys [mailto:address@hidden 
> Sent: Tuesday, May 25, 2004 2:20 PM
>
<SNIP> 
> This was also an opportunity for me to take a closer look at 
> your code. I still have some remarks:
> 
>  * We want to separate formatting machinery from syntax.  
> Your fret-diagram command accepts a string containing items 
> separated by semicolons.  It would be better style to put the 
> items in a Scheme list, eg.
> 
>   \fret-diagram-verbose #0.75 #'(6-x 5-x 4-o 1-2)
> 
> or even better,
> 
>   \fret-diagram-verbose #0.75
>     #'((cross 6) (cross 5) (open 4) (barre 1 2))
> 

I'm delighted to make this change.  Thanks for the input on how you'd
like to do it.


> A separate frontend could translate the current string syntax 
> to a Scheme list. 
> 
>  * The diagram items include settings for linethickness, height,
>    width, etc.
> 
>    It would be better style to put these settings into properties, so
>    you could do
> 
>          \translator { \StaffContext
>            \override FretDiagram #'thickness = #0.2
>          }
> 
>    and change all fret diagrams in one fell swoop.
> 
>    The properties delivered to the markup command through the props
>    argument (which is a list of alists)
>

So do I assume that props is provided by the context, and that I can
just get the value out of props with appropriate (assoc * ) calls?  Can
you give me some suggestions as to where I'd go to find good examples of
working with props?
 
>  * for multi-choice alternatives, such as
> 
>          f:number -- set fingering label type (0 = none, 1 = in circle
>                   on string, 2 = below string) Default 0
> 
>    we use symbols instead of numbers. They are more descriptive.

Of course this is the best way.  Should I define a symbol to a numeric
value, like in translate-stencil (X = 0, Y = 1), or is it better to just
have the code say (if eq? markingcode below)?

> 
>  * For the same reason, I frown on single character command
>    names. Write
> 
> 
>      thickness, barre, radius
> 
>    instead of
> 
>      t, c, d
> 

No problem.  I can easily see the advantage

>  * for alists, we generally use symbols, not strings as keys.

So instead of having an alist entry be ("thickness" 0.5)  it would be
(thickness 0.5)?

> 
>  * Unlike LISP, Scheme does not have nil pre-defined. Simply use '()
> 
Ooops -- I'll fix it.

>  * It would be nice if the width of a diagram were computed, from the
>    length of the stringTunings property.

And I assume I get stringTunings I get that from an alist in the props?

> 
>  * linethicknesses are generally expressed relative to the
>    linethickness \paper variable. The default usually is 1.0

Is that also in the props?  If not, how do I get hold of it?

> 
> 
> I should be grateful if you could address these issues.

I'll be happy to do it.  I'm sure I'll need some more guidance as I get
into it, but I'll let you know.

Carl