Re: [Patch:] Negative fret numbers cause a warning (issue 1035)

[Carl Sorensen]

On 12/23/10 3:27 AM, "Marc Hohl" <address@hidden> wrote:

> Am 22.12.2010 22:02, schrieb Carl Sorensen:
>> 
>> 
>> On 12/22/10 4:16 AM, "Marc Hohl"<address@hidden>  wrote:
>> 
>>> Am 22.12.2010 09:48, schrieb Carl Sorensen:
>>> Hmmm - I wrote some tunes with a capo placed at the third fret but covering
>>> only strings one upto five, so the sixth string still sounds with an open e.
>>> 
>>> I didn't wrote it down, but if I ever do so, I wonder whether the open e
>>> would be written as fret number "-3" in tablature relative to the capo
>>> position.
>> Hmm -- I wouldn't write things down relative to a partial capo.  I think the
>> meaning of a 1 on the e string is unclear if you do that.  Does it mean the
>> first fret or the fourth fret?
>> 
>> If I were writing music with a partial capo, I'd probably write everything
>> relative to the nut.  Or perhaps I'd change the string tunings to reflect
>> the presence of the capo and indicate somewhere on the score that frets were
>> relative to the capo on the capo'ed strings and relative to the nut on the
>> non-capo'ed strings.
> Well, this seems to be a rather philosophical question, but assume
> I have a partial capo on strings 1-5 and I want to play a Bflat major chord
> in G shape.
> 
> A pattern like
> 
> Capo III (1-5)
> 
> -3-
> -3-
> -0-
> -0-
> -2-
> -3-
> 
> seems to me more readable/understandable than
> 
> Capo III (1-5)
> 
> -3-
> -3-
> -0-
> -0-
> -2-
> -6-
> 
> which at first glance looks like only Allan Holdsworth would be able to
> play ;-)

I can see your point here.

I suspect that our major reason for disagreeing on this is that you are
mostly concerned about tablature, while I'm mostly concerned about fret
diagrams.  Negative fret numbers aren't currently supported in fret
diagrams, and I don't think that they should be.  The Capo III (1-5) would
be shown in the fret diagram by a capo indicator on the third fret, rather
than by an adjustment in all the fret numbers.

> 
>>> Despite this rather artificial example, I don't know whether we should make
>>> lilypond more "intelligent". Sometimes I did make some octavation errors and
>>> spotted the erroneous negative numbers after printing the scores and handing
>>> out the copies to my students (therefore way too late ;-) - the string
>>> number
>>> was right indeed, but I forgot a "'".
>> OK, so in this case, you didn't see the negative numbers because they were
>> part of the tablature.  Your tablature ended up clearly wrong -- the
>> tablature literally couldn't be played.
> Yes, but in this case the normal staff is wrong, too, so I have to rework
> it in any case.
>> The warning here shows that there is a mistake.  The fact that we were
>> missing a warning is a bug, and we really need to add a warning.
> Yes, of course.
>> [...]
>> I think we agree on the fact that a warning should be printed.  The only
>> remaining issue is what to do with the note having the negative fret number.
>> I see three possible choices (and all are achievable with code).
>> 
>> A) Go ahead and include the negative fret number in the tablature and the
>> fretboard.  In terms of fretboards, this might be preferred behavior,
>> because the fretboard will be ugly and should be easily visible.  In terms
>> of tablature, I think this is the worst behavior, because it creates an
>> impossible note to play and it's not clearly visible.
> You're right, but I have to take the warning into account (as with
> open strings, unterminated ties and more). If I know that there is something
> wrong with my tablature and I have to search for a negative fret number,
> I'll find it very soon.

I agree.

>> B) Leave the note out of the fretboard and the tablature.  This makes no
>> assumption about the relative importance of the pitch vs. the string.  Since
>> we don't know where the error is, we just drop the note.  This has the
>> advantage that the music is playable, but the major disadvantage (IMO) that
>> there is no evidence in the music that something isn't right (unless you
>> have both Staff notation and TabStaff notation, where you can see there is
>> a missing pitch).
>> 
>> C) Try to find a string that will allow the note to be played.  This assumes
>> that the pitch is right, and then tries to make the tablature match the
>> pitch.  In this case, the TabStaff will always reflect the notes on the
>> Staff if possible.
>> 
>> Your preference, as reflected in the patch, is to do A.
>> 
>> My preference is to do C, because I think that the TabStaff should always
>> match the Staff if possible.  That's the behavior I chose (and you agreed
>> with my reasoning) when dealing with an improperly labeled open string.
> C sounds reasonable, but it will cause lilypond not to allow for
> negative frets without hacking the fret number printing callback,
> and while I don't know whether it is standard, I think *I* will probably
> need them in the future. So for me, the warning is ok, saying
> "hey, you are specifying negative fret numbers, I hope you know what
> you do" - and if it is a "normal" piece of music, I will check the resulting
> score for these errors, as I would do for things like a ~ b .
> 
> But I am open for discussions on this, of course ...

Well, if you really want negative fret numbers, then let's go ahead with
your patch.  I don't want them (in fretboards), but I'll have both a warning
and a broken fretboard if they're used, so it's no problem.

I'll push your patch.

Thanks,

Carl


> 
>> [...]
>> 
>> Thanks for all your work on LilyPond, and for your work on this issue in
>> particular.
> Well, I still think I should spend more time on lilypond, and for 2011,
> I'll give it another try, but that's another issue...
> 
> Thanks for your kind words!
> 
> Regards,
> 
> Marc
>