Re: Issue 2026 in lilypond: Make markup utility definitions available via new (scm markup-utility-defs) scheme module

[lilypond]

Updates:
        Status: Started
        Labels: Patch-needs_work

Comment #32 on issue 2026 by address@hidden: Make markup utility  
definitions available via new (scm markup-utility-defs) scheme module
http://code.google.com/p/lilypond/issues/detail?id=2026

Caused docs build to fail in Documentation/ly-examples/chart.ly.

Apparently fails in a markup? call. I had added code to lily.scm to handle  
throws from the markup code and this showed up as 'unbound variable  
empty-markup.  Further fettling of the handling code and a change to using  
the detailed markup-thrower-typecheck for markup? showed the problem that  
the markup? predicate couldn't cope with processing a (0 . 0) pair.

It turns out we have had a lurking bug in define-markup-commands.scm caused  
by this
code:
(define-public (empty-markup)
  (make-simple-markup ""))

This was working as long as we were basically turning a blind eye to throws  
in the run-time guile procedures in lily.scm.  As soon as we started  
catching throws other than 'ly-failed-file, errors from this procedure  
surfaced.  'empty-markup' is used in lots of places in chord-processing  
fretboard and tablature code scheme code.  This is fixed if we move the  
definition of the \null markup to the before the empty-markup declaration  
and change empty-markup to
(define-public (empty-markup)
  make-null-markup))
I've tested this with a minimal changes patch on a branch from master which  
I've attached.  It's built the docs successfully and run reg-tests OK.   
I've attached a patch-file.

I'll merge these changes into my local T2026 branch and upload an amended  
patch-set to Rietveld for review.

Cheers, Ian


Attachments:
        0001-T2026-1-minimal-fix-for-T2026.patch  6.5 KB