~ chicken-core (chicken-5) 1b0996e966da46d3bb02dc46a6dab3545fe5cbbe

commit 1b0996e966da46d3bb02dc46a6dab3545fe5cbbe
Author:     unknown <felix@.(none)>
AuthorDate: Tue Nov 3 14:50:33 2009 +0100
Commit:     unknown <felix@.(none)>
CommitDate: Tue Nov 3 14:50:33 2009 +0100

    import-library is only generated if changed or doesn't exist (suggested by Joerg Wittenberger)

diff --git a/compiler.scm b/compiler.scm
index 7680ec99..8ae2907d 100644
--- a/compiler.scm
+++ b/compiler.scm
@@ -485,21 +485,27 @@
        '() ) ))
 
   (define (emit-import-lib name il)
-    (let ((fname (if all-import-libraries
-		     (string-append (symbol->string name) ".import.scm")
-		     (cdr il))))
-      (when verbose-mode
-	(print "generating import library " fname " for module "
-	       name " ..."))
-      (with-output-to-file fname
-	(lambda ()
-	  (print ";;;; " fname " - GENERATED BY CHICKEN "
-		 (chicken-version) " -*- Scheme -*-\n")
-	  (for-each
-	   pretty-print
-	   (##sys#compiled-module-registration
-	    (##sys#current-module)))
-	  (print "\n;; END OF FILE")))))
+    (let* ((fname (if all-import-libraries
+		      (string-append (symbol->string name) ".import.scm")
+		      (cdr il)))
+	   (imps (##sys#compiled-module-registration (##sys#current-module)))
+	   (oldimps
+	    (and (file-exists? fname)
+		 (read-file fname) ) ) )
+      (cond ((equal? imps oldimps)
+	     (when verbose-mode
+	       (print "not generating import library `" fname "' for module `" 
+		      name "' because imports did not change")) )
+	    (else
+	     (when verbose-mode
+	       (print "generating import library `" fname "' for module `"
+		      name "' ..."))
+	     (with-output-to-file fname
+	       (lambda ()
+		 (print ";;;; " fname " - GENERATED BY CHICKEN "
+			(chicken-version) " -*- Scheme -*-\n")
+		 (for-each pretty-print imps)
+		 (print "\n;; END OF FILE"))))) ) )
 
   (define (walk x e se dest)
     (cond ((symbol? x)