convert-ly: option to only modify changed files. (issue2642041)

[percival . music . ca]

Reviewers: ,

Message:
Pretty simple, but useful.

Description:
convert-ly: option to only modify changed files.

This useful for the regtests -- with the extra -d flag, we will
only change the \version string if the actual contents of the file
has changed.  This lets us see which tests were modified, and
which tests were unchanged since the previous stable release.

Please review this at http://codereview.appspot.com/2642041/

Affected files:
  M scripts/convert-ly.py


Index: scripts/convert-ly.py
diff --git a/scripts/convert-ly.py b/scripts/convert-ly.py
index  
a1f126f29093265e5d3d3a74225b699e423ddd3b..29aaae51f5d140c0204a0fd70c63b5b8a773da0f  
100644
--- a/scripts/convert-ly.py
+++ b/scripts/convert-ly.py
@@ -118,6 +118,12 @@ def get_option_parser ():
               action='store_true',
               dest='force_current_version',
               default=False)
+
+    p.add_option ('-d', '--diff-version-update',
+              help=_ ("only update \\version number if file is modified"),
+              action='store_true',
+              dest='diff_version_update',
+              default=False)

     p.add_option ("-s", '--show-rules',
               help=_ ("show rules [default: -f 0, -t %s]") %  
program_version,
@@ -250,6 +256,11 @@ def do_one_file (infile_name):
         if global_options.force_current_version and last == to_version:
             last = str_to_tuple (program_version)

+        if global_options.diff_version_update:
+            if result == input:
+                # make no (actual) change to the version number
+                last = from_version
+
         newversion = r'\version "%s"' % tup_to_str (last)
         if lilypond_version_re.search (result):
             result = re.sub (lilypond_version_re_str,