Re: make-engraver helper macro (issue 5672085)

[dak]

Reviewers: carl.d.sorensen_gmail.com,

Message:
On 2012/02/18 16:19:35, Carl wrote:
> Looks excellent to me!

> Makes Scheme engravers much more accessible.

Well, it is just syntactic sugar (or rather skimming).  But it would
appear that working with quoting and quasiquoting and unquoting and cons
and lambda and list even on an elementary level is rather scary to
people not quite into Scheme, and you don't have to enter "any of this
nonsense" manually.  It turns out that the commit putting this macro to
use removes about as much lines as the commit defining the macro adds.

I am not particularly happy about the discoverability.

Description:
make-engraver helper macro

Two commits, the actual new functionality being introduced in
scm/translation-functions.scm (is that the proper place?), and the
rest just usages of this macro.

This is an evidently upwards-compatible change.

Please review this at http://codereview.appspot.com/5672085/

Affected files:
  M  
Documentation/snippets/new/defining-an-engraver-in-scheme-ambitus-engraver.ly
  M Documentation/snippets/new/numbers-as-easy-note-heads.ly
  M input/regression/scheme-engraver-instance.ly
  M input/regression/scheme-engraver.ly
  M input/regression/scheme-text-spanner.ly
  M ly/event-listener.ly
  M scm/translation-functions.scm