Re: input/regression/scheme-text-spanner.ly: fix problem with constants (issue 11614044)

[david . nalesnik]

On 2013/07/23 15:06:51, dak wrote:
> On 2013/07/23 13:52:13, david.nalesnik wrote:

> > Sorry, replied a bit hastily!

> [...]

> > I've thought some more about the issue of trying to change constants
elsewhere
> > in the file.
> >
> > Specifically, regarding the addition of the new grob description to
> > all-grob-descriptions, would the following be any better?
> >
> > So, as I understand it, remove add-grob-description, duplicating its
changes
> to
> > the description of 'SchemeTextSpanner, and creating a new variable
to avoid
> > tampering with all-grob-descriptions, using that new variable in the
layout
> > block.

> No, that's not necessary.  all-grob-descriptions is defined as a
session
> variable, so it will be restored at the end of the session.  You must
not change
> it _destructively_ (meaning that you must not change any of its cons
cells or
> what they point to), but you can replace with a different list as a
whole.

> Since the code only added to the _front_ of all-grob-descriptions,
this part was
> entirely harmless.

> The problem is rather with the code in "complete-grob-entry" or what
it was.
> That one worked destructively on constant lists (like, one may add,
our current
> code for creating all-grob-descriptions originally does).

> So what is being done is just as bad as our existing code elsewhere,
but there
> is no interference with it.

> The part adding stuff to the front of all-grob-descriptions is fine by
itself.

Hmmm, so if I understand correctly:

The problem in the regtest is that add-grob-definition should not be
applied to the quasiquoted list. In doing so, however, nothing is being
done that doesn't have precedent in define-grobs.scm.

I'm not understanding from your answer if you'd like me to change
anything here, though.

I hesitate to do something like the following!

#(add-grob-definition
  'SchemeTextSpanner
  (list
    (cons
      'bound-details
      (list
        (cons 'left
              (list
                (cons 'Y 0)
                (cons 'padding 0.25)
                (cons 'attach-dir LEFT)))
        (cons 'left-broken
              (list
                 (cons 'end-on-note #t)))
        (cons 'right
              (list
                (cons 'Y 0)
                (cons 'padding 0.25)))))
    (cons 'dash-fraction 0.2)
    (cons 'dash-period 3.0)
    (cons 'direction UP)
    (cons 'font-shape 'italic)
    (cons 'left-bound-info ly:line-spanner::calc-left-bound-info)
    (cons 'outside-staff-priority 350)
    (cons 'right-bound-info ly:line-spanner::calc-right-bound-info)
    (cons 'staff-padding 0.8)
    (cons 'stencil ly:line-spanner::print)
    (cons 'style 'dashed-line)
    (cons 'meta
          (list
            (cons 'class 'Spanner)
            (cons 'interfaces
                  (list
                    'font-interface
                    'line-interface
                    'line-spanner-interface
                    'side-position-interface))))))

https://codereview.appspot.com/11614044/