patch::: 1.3.136.jcn1

[lilypond.git] / scm / tex.scm

diff --git a/scm/tex.scm b/scm/tex.scm
index aad55f430ceeb0d587df06046811e6ad0ac44fed..44cf91f0fa569a7d47a8f153d8c01170e7811a04 100644 (file)
--- a/scm/tex.scm
+++ b/scm/tex.scm
@@ -133,15 +133,17 @@
          s))
       
   (define (lily-def key val)
-    (string-append
-     "\\def\\"
-     (if use-regex
-        ;; fixed in 1.3.4 for powerpc -- broken on Windows
-        (regexp-substitute/global #f "_"
-                                  (output-tex-string key) 'pre "X" 'post)
-        (output-tex-string key))
-     "{" (output-tex-string val) "}\n"))
-
+    (let ((tex-key
+          (if use-regex
+              ;; fixed in 1.3.4 for powerpc -- broken on Windows
+              (regexp-substitute/global
+               #f "_" (output-tex-string key) 'pre "X" 'post)
+              (output-tex-string key)))
+         (tex-val (output-tex-string val)))
+      (if (equal? (sans-surrounding-whitespace tex-val) "")
+         (string-append "\\let\\" tex-key "\\undefined\n")
+         (string-append "\\def\\" tex-key "{" tex-val "}\n"))))
+               
   (define (number->dim x)
     (string-append
      ;;ugh ly-* in backend needs compatibility func for standalone output