Merge pull request #16 from vslavik/diff

Add --diff-only option to only see changes to the generated files.

src/bkl/io.py

@@ -37,6 +37,9 @@
 # Set to true to prevent any output from being written
 dry_run = False
 
+# Set to true to show diff with the existing file instead of updating it
+diff_only = False
+
 # Set to true to force writing of output files, even if they exist and would be
 # unchanged. In other words, always touch output files. This is useful for
 # makefiles that support automatic regeneration.
@@ -124,6 +127,15 @@ def commit(self):
                 status = "."
                 logger.info("%s\t%s", status, rel_fn)
                 return
+            if diff_only:
+                import sys
+                from difflib import unified_diff
+                for line in unified_diff(old.splitlines(True) if old is not None else [],
+                                         self.text.splitlines(True),
+                                         os.path.normpath(os.path.join("old", self.filename)),
+                                         os.path.normpath(os.path.join("new", self.filename))):
+                    sys.stdout.write(line)
+                return
         else:
             old = None
 

src/tool.py

@@ -89,6 +89,10 @@ def get_version(self):
         "", "--dry-run",
         action="store_true", dest="dry_run", default=False,
         help="don't write any files, just pretend to do it")
+parser.add_option(
+        "", "--diff-only",
+        action="store_true", dest="diff_only", default=False,
+        help="only output diffs instead of modiyfing the files, implies --dry-run")
 parser.add_option(
         "", "--force",
         action="store_true", dest="force", default=False,
@@ -129,6 +133,9 @@ def get_version(self):
     log_level = logging.WARNING
 logger.setLevel(log_level)
 
+if options.diff_only and options.force:
+    sys.stderr.write("--diff-only and --force option can't be used together\n")
+    sys.exit(3)
 
 # note: we intentionally import bakefile this late so that the logging
 # module is already initialized
@@ -140,6 +147,7 @@ def get_version(self):
 try:
     start_time = time()
     bkl.io.dry_run = options.dry_run
+    bkl.io.diff_only = options.diff_only
     bkl.io.force_output = options.force
     if options.dump:
         intr = bkl.dumper.DumpingInterpreter()