Provide script/gypi support for manifest generation

chrome/browser/resources/chromeos/chromevox/tools/merge_manifests.py

+#!/usr/bin/env python
+
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import json

[Peter Lundblad, 2014/05/22 00:28:25]

Care to provide a minimal docstring?

[David Tseng, 2014/05/22 02:42:04]

Done.

+import optparse
+import sys
+
+def MergeManifests(base, override, output):
+  ''' Takes two extension manifests and merges them into an output manifest.

[Peter Lundblad, 2014/05/22 00:28:25]

Nit: space after '''

[David Tseng, 2014/05/22 02:42:04]

Remove it?
+  ''' Takes two extension manifests and merges them into an output manifest.

+
+  Args:
+    base: path to a extension manifest.
+    override: path to a extension manifest.
+    output: path to the result of merging base and override.
+  '''
+  base_file = open(base)
+  override_file = open(override)

[Peter Lundblad, 2014/05/22 00:28:25]

Consider using with to have these automatically closed.

[David Tseng, 2014/05/22 02:42:04]

Done. (Nice construct).

+  base_manifest = json.load(base_file)
+  override_manifest = json.load(override_file)
+  MergeDicts(base_manifest, override_manifest)
+  json.dump(base_manifest, open(output, 'w'), sort_keys=True, indent=2)

[Peter Lundblad, 2014/05/22 00:28:25]

Can you put the open call out of line and close the file afterwards?

[David Tseng, 2014/05/22 02:42:04]

Done.

+
+
+def MergeDicts(base, override):
+  '''Merges override into base.
+
+  Args:
+    base: dictionary with base key values.
+    override: dictionary with key values to insert (and possibly overwrite) in
+        base.
+  '''
+  for key in override:
+    if type(override[key]) is dict:
+      MergeDicts(base, override[key])

[Peter Lundblad, 2014/05/22 00:28:25]

Shouldn't you merge override into base[key], creating it if it doesn't exist?

[David Tseng, 2014/05/22 02:42:04]

yYup; goofed on this case; also handle the case when base[key] is not a dict.

+    else:
+      base[key] = override[key]
+
+
+def main():
+  parser = optparse.OptionParser(description=__doc__)
+  parser.usage = ('%prog [options] <base_manifest_path>'
+                  ' <override_manifest_path> <output_manifest_path>')

[Peter Lundblad, 2014/05/22 00:28:25]

I recommend making the out file an -o option to be consistent with many other
scripts.

+  _, args = parser.parse_args()
+  if len(args) != 3:
+    print >>sys.stderr, 'Expected exactly three arguments'
+    sys.exit(1)
+  MergeManifests(args[0], args[1], args[2])
+
+if __name__ == '__main__':
+  main()