Issue 3995: Rename 'thin-kern to 'segno-kern.

was: Remove thin-kern property.
was: Clarify BarLine props 'kern and 'thin-kern.

Issue on tracker:
http://code.google.com/p/lilypond/issues/detail?id=3995

[Mark Polesky, 2014-07-06 06:46:53]

Hi, I'm proposing to get rid of the BarLine.thin-kern property with this patch,
so if you're opposed, let me know.

You can see my comments/rationale here:
http://code.google.com/p/lilypond/issues/detail?id=3995

Thanks,
Mark

[marc, 2014-07-06 08:09:57]

On 2014/07/06 06:46:53, Mark Polesky wrote:
> Hi, I'm proposing to get rid of the BarLine.thin-kern property with this
patch,
> so if you're opposed, let me know.
> 
> You can see my comments/rationale here:
> http://code.google.com/p/lilypond/issues/detail?id=3995
> 
> Thanks,
> Mark

I don't see any reason to maintain two different types of kern that are never
used independently, so LGTM.

[thomasmorley651, 2014-07-06 11:52:56]

On 2014/07/06 06:46:53, Mark Polesky wrote:
> Hi, I'm proposing to get rid of the BarLine.thin-kern property with this
patch,
> so if you're opposed, let me know.
> 
> You can see my comments/rationale here:
> http://code.google.com/p/lilypond/issues/detail?id=3995
> 
> Thanks,
> Mark

I disagree!
'kern and 'thin-kern _are_ used differently.
Look at the output from:

\version "2.19.8"

\paper { ragged-right = ##f }

{
  a'1
  \mark "default"
  \bar ":|.S"
  b'
  \once \override Staff.BarLine #'kern = #10
  \mark "'kern 10"
  \bar ":|.S"
  c'
  \once \override Staff.BarLine #'thin-kern = #10
  \mark "'thin-kern 10"
  \bar ":|.S"
  d'
  \once \override Staff.BarLine #'kern = #10
  \once \override Staff.BarLine #'thin-kern = #10
  \mark \markup \column { "'kern 10" "'thin-kern 10" }
  \bar ":|.S"
  e'
}

More:
http://code.google.com/p/lilypond/issues/detail?id=3995

[Mark Polesky, 2014-07-06 12:53:55]

On 2014/07/06 11:52:56, thomasmorley651 wrote:
> I disagree!
> 'kern and 'thin-kern _are_ used differently.
> Look at the output from:

Harm,

what am I missing?  To my eye (compiling this with the latest snapshot), your
example shows that thin-kern does nothing.  

- Mark

[thomasmorley651, 2014-07-06 13:19:35]

On 2014/07/06 12:53:55, Mark Polesky wrote:
> On 2014/07/06 11:52:56, thomasmorley651 wrote:
> > I disagree!
> > 'kern and 'thin-kern _are_ used differently.
> > Look at the output from:
> 
> Harm,
> 
> what am I missing?  To my eye (compiling this with the latest snapshot), your
> example shows that thin-kern does nothing.  
> 
> - Mark

Look at the underlaying double-bar-line.
I'll post an image, with a colored double-bar on the tracker.

[marc, 2014-07-06 20:43:26]

Am 06.07.2014 13:52, schrieb thomasmorley65@gmail.com:
> On 2014/07/06 06:46:53, Mark Polesky wrote:
>> Hi, I'm proposing to get rid of the BarLine.thin-kern property with
> this patch,
>> so if you're opposed, let me know.
>
>> You can see my comments/rationale here:
>> http://code.google.com/p/lilypond/issues/detail?id=3995
>
>> Thanks,
>> Mark
>
> I disagree!

D'oh – I should have known better, having written the code for the segno
bar line.

Marc

[Mark Polesky, 2014-07-07 01:31:01]

On 2014/07/06 11:52:56, thomasmorley651 wrote:
> I disagree!
> 'kern and 'thin-kern _are_ used differently.

Okay, so then it's just a question of clarifying the misleading docstrings.  How
about this?

kern
  The space between individual elements in any compound bar line.

thin-kern
  The space between the two thin lines of the segno bar line symbol.

I've updated the patch accordingly.

[marc, 2014-07-07 07:25:15]

On 2014/07/07 01:31:01, Mark Polesky wrote:
> On 2014/07/06 11:52:56, thomasmorley651 wrote:
> > I disagree!
> > 'kern and 'thin-kern _are_ used differently.

But *do* we need two different variables which then are used with exactly the
same value?
Do we need the option to change the distance of the segno double bar line?

IIRC, this is a leftover from the bar line reorganisation work, the double
bar line "||" was formerly spaced with 'thin-kern as well, but as we
implemented the stacking algorithm for bar lines, all constituents are now
spaced with 'kern.

I'd remove 'thin-kern entirely. In case someone wants to modify the appearance
of the segno symbol, he can use a multiplier and create his own stencil easily.
 
> Okay, so then it's just a question of clarifying the misleading docstrings. 
How
> about this?
> 
> kern
>   The space between individual elements in any compound bar line.
> 
> thin-kern
>   The space between the two thin lines of the segno bar line symbol.
> 
> I've updated the patch accordingly.

[thomasmorley651, 2014-07-07 22:13:27]

On 2014/07/07 07:25:15, marc wrote:
> On 2014/07/07 01:31:01, Mark Polesky wrote:
> > On 2014/07/06 11:52:56, thomasmorley651 wrote:
> > > I disagree!
> > > 'kern and 'thin-kern _are_ used differently.
> 
> But *do* we need two different variables which then are used with exactly the
> same value?
> Do we need the option to change the distance of the segno double bar line?

I'd say yes.
I'm always against loosing functionality, and deleting 'thin-kern would limit
the tweaking-possibilities.
 
> IIRC, this is a leftover from the bar line reorganisation work, the double
> bar line "||" was formerly spaced with 'thin-kern as well, but as we
> implemented the stacking algorithm for bar lines, all constituents are now
> spaced with 'kern.

Yep

> I'd remove 'thin-kern entirely. In case someone wants to modify the appearance
> of the segno symbol, he can use a multiplier and create his own stencil
easily.

It's very easy to create custom-bar-lines nowadays -- for us!
Though, I doubt the average user has the scheme-knowledge to do so.

In the NR we don't explain how to code new barline-procedures like
`make-segno-bar-line' (only the hint to look into bar-line.scm) and afaik
nowhere else.
There's a regtest doing so, but we don't expect users to look there.

Until we can come up with an interface to create new barline-procedures, which
is much easier for the average user (although I've no clue right now, how it
should look), we should keep all tweaking/overriding possibilities, imho.

[Mark Polesky, 2014-07-08 18:20:41]

marc wrote:
> OK, but 'thin-kern does not seem to be an
> appropriate name for this property anymore IMHO.

How about 'segno-kern?  (patch updated accordingly)

[marc, 2014-07-09 07:06:54]

Am 08.07.2014 20:20, schrieb markpolesky@gmail.com:
> marc wrote:
>> OK, but 'thin-kern does not seem to be an
>> appropriate name for this property anymore IMHO.
>
> How about 'segno-kern?  (patch updated accordingly)

Much better!