Re: Add option to indicate frets by letters in tablature (issue164063)

[Trevor Daniels]

Carl Sorensen wrote Sunday, December 06, 2009 9:59 PM
> On 12/6/09 9:50 AM, "Trevor Daniels" <address@hidden> 
> wrote:
> > I changed it because "string" is a keyword in Scheme.
> > It is even used as such in the same few lines of code.
> > Although "string" can be used as a variable name I don't
> > think it should be - it seems bad practice to overload
> > keywords in this way.
>
> I don't know of string as a keyword in Scheme.  It's not listed in 
> the Guile
> reference manual index.
>
> string?  is a predicate.
>
> substring is a procedure.
>
> There are a bunch of string-*, string->*, and *->string 
> procedures.
>
> But string by itself seems to not be part of the Scheme language. 
> Have I
> missed something? (I easily could have.)

I think you have.  string is a built-in procedure which
forms a string from one or more characters.  Try

guile> (string #\a #\b)

It outputs "ab".

It's actually used in the code in question, which was
what prompted me to change it.  "string" was being used
with two meanings in the same procedure.

> > I fully agree with your point in general, but we need
> > to think of a variable name other than "string" for the
> > string on an instrument.  I tried, and failed :(, hence
> > str.
>
> Dana suggests "course", which I guess speaks well to lute players. 
> But not
> to guitar players.
>
> string seems the best to me.

I prefer str to course and string, but if no other ideas
are forthcoming I'll use string_number.

> > > http://codereview.appspot.com/164063/diff/2001/3008#newcode399
> > > scm/translation-functions.scm:399: (make-vcenter-markup
> > > If length of 'fretLetterExceptions is greater than zero, I think
> > > we
> > > ought to throw a warning if fret is higher than the length of
> > > 'fretLetterExceptions so that the user will have an idea of why
> > > things
> > > didn't work the way they wanted it to.
> >
> > Hhm, I'm not so sure about this.  I had envisaged changing
> > only the c to r, leaving all letters beyond c to default.
> > As this would be the norm I don't think a warning is desirable,
> > but I'm willing to be convinced otherwise.  Actually, for most
> > ancient instruments only i or j, not both, is used, so maybe the
> > length of fretLetterExceptions would be somewhat greater than
> > 3 normally, making a warning more appropriate.  Although if i
> > not j is a general rule, maybe that should be built in to the
> > default, then we'd be back to needing just the change from c to 
> > r.
> > Maybe a question on -user is needed on this point.
>
> I had envisioned that a full set of fretLetters would be given (in 
> fact, I'm
> not really a big fan of the term fretLetterExceptions).  But now 
> that I see
> your design intent, I'm not sure what the best thing to do is.
>
> Perhaps we just ought to define lists called fretLabels (instead 
> of
> fretLetters).  And we could then define lists of any kind of 
> glyphs to be
> used.  There could be specific lists for each different style of 
> tablature,
> that would be very easy to switch to.  The fretLabels list 
> wouldn't need to
> be characters; they could be markups or stencils, so users could 
> define
> whatever is needed or desired.

I quite like the term fretLabels, with the list being of
anything that evaluated to a Scheme string.  I'll have a
play with this idea.  I think I shall also drop the idea
of having the default fret labels being the alphabet and
require all labels to be provided, issuing a warning as
you suggested if insufficient are available to indicate
the required pitch.  Label sets can then be provided in
the context definitions or by the user.

Trevor