new script to update untranslated messages from other language file

gluon/languages.py

@@ -995,6 +995,23 @@ def update_all_languages(application_path):
             findT(application_path, language[:-3])
 
 
+def update_from_langfile(target, source):
+    """this will update untranslated messages in target from source (where both are language files)
+    this can be used as first step when creating language file for new but very similar language
+        or if you want update your app from welcome app of newer web2py version
+        or in non-standard scenarios when you work on target and from any reason you have partial translation in source
+    """
+    src = read_dict(source)
+    sentences = read_dict(target)
+    for key in sentences:
+        val = sentences[key]
+        if not val or val == key:
+            new_val = src.get(key)
+            if new_val and new_val != val:
+                sentences[key] = new_val
+    write_dict(target, sentences)
+
+
 if __name__ == '__main__':
     import doctest
     doctest.testmod()

scripts/lang_update_from_langfile.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+This script will update untranslated messages in target from source (target and source are both language files)
+Usage:
+    this can be used as first step when creating language file for new but very similar language
+    or if you want update your app from welcome app of newer web2py version
+    or in non-standard scenarios when you work on target and from any reason you have partial translation in source
+"""
+
+import sys
+import os
+sys.path.append(os.path.join(*__file__.split(os.sep)[:-2] or ['.']))
+
+from gluon.languages import update_from_langfile
+import argparse
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Use to set untranslated messages in the translation file from another one.')
+    parser.add_argument(
+        '-t', '--target',
+        required=True,
+        dest="target",
+        help="Specify language file (rw) where untranslated messages will be updated if possible"
+    )
+    parser.add_argument(
+        '-s', '--source',
+        required=True,
+        dest="source",
+        help="Specify language file (ro) where seek for translations"
+    )
+    args = parser.parse_args()
+
+    update_from_langfile(args.target, args.source)
+
+    print '%s was updated.' % args.target