Lines and Ties and Slurs oh my!

[steve]

 Howdy!

      It is well known that Ties and Slurs are problematic in LilyPond
2.18.0. As can be seen by
a simple example from my project "Goldberg Variations for Guitar Ensemble"
variation 22

         http://www.gooeytar.com/projects/BWV-988/test/test.orig.pdf

         Notice that Ties in bar 1 are different than Ties in bar 2 or bar
4 or bar 7. Termination
 of the Tie is not consistent.

          So first we need to ask the question: How should Ties be drawn?
Specifically
where should the Tie terminate relative to the notehead?

          Ties in bar 1 and bar 3 terminates at the "inside upper corner"
of the notehead. Ties in
bar 4 and 7, terminate "above / below and in the middle" of the notehead.
Which is
correct?

         My understanding is that the Ties in bar 1 and 3 are correct.
Slurs should
terminate in the middle of the note to distinguish between Ties. Is that the
consensus with Lilypond users / dev?

         Is there a general fix for this across the broad section of
examples?

        One solution is to use \shape to fix individual Ties. If I define
a couple of
macros

     * to fix ties in bar 4, 13  (TieDown_stemsUpUp)
TDUUa = \shape #'((0.6 . 0.4)(0 . 0.6)(0 . 0.6)(-0.6 . 0.4)) Tie

    * to fix ties in bar 7 (TieUp_stemsDownDown)
TUDDa =  \shape #'((0.6 . -0.2)(0 . -0.3)(0 . -0.3)(-0.6 . -0.2)) Tie


       The results of the above can be seen here

http://www.gooeytar.com/projects/BWV-988/test/test.pdf

       Are they correct now? Is there another better way to deal with this?

       It is certainly possible to go through the 100+ or so "bad" Ties
manually and I expect
that there are simple fixes like the above that will correct common
categories
of bad Ties; for example all Ties between notes that are on upper ledger
lines with
stems down are drawn incorrectly with termination in the middle of the
notehead (like a slur).
Some preliminary testing has led me to conclude that the same fix (like
above) may typically
fix the same situation regardless of the length of the Tie or the value of
the notes....

       Is there a way to integrate this heuristic into the main code so
that most manual
tweaking is not needed?

      Or is there another better approach that can be used for issue?

      thanx - steve