Added --previous flag to msgmerge command used by makemessages

Also took the opportunity to slightly refactor gettext options
so as to ease customization by subclassing the command.
Thanks Michal Čihař for the report and initial patch.

1 files changed, 23 insertions, 34 deletions

diff --git a/django/core/management/commands/makemessages.py b/django/core/management/commands/makemessages.py
index 9c81bc8e20..7c2555ba2f 100644
--- a/django/core/management/commands/makemessages.py
+++ b/django/core/management/commands/makemessages.py
@@ -80,14 +80,8 @@ class TranslatableFile(object):
                 '--keyword=ngettext_lazy:1,2',
                 '--keyword=pgettext:1c,2',
                 '--keyword=npgettext:1c,2,3',
-                '--from-code=UTF-8',
-                '--add-comments=Translators',
                 '--output=-'
-            ]
-            if command.wrap:
-                args.append(command.wrap)
-            if command.location:
-                args.append(command.location)
+            ] + command.xgettext_options
             args.append(work_file)
         elif domain == 'django' and (file_ext == '.py' or file_ext in command.extensions):
             thefile = self.file
@@ -115,14 +109,8 @@ class TranslatableFile(object):
                 '--keyword=npgettext:1c,2,3',
                 '--keyword=pgettext_lazy:1c,2',
                 '--keyword=npgettext_lazy:1c,2,3',
-                '--from-code=UTF-8',
-                '--add-comments=Translators',
                 '--output=-'
-            ]
-            if command.wrap:
-                args.append(command.wrap)
-            if command.location:
-                args.append(command.location)
+            ] + command.xgettext_options
             args.append(work_file)
         else:
             return
@@ -206,6 +194,11 @@ class Command(NoArgsCommand):
     requires_system_checks = False
     leave_locale_alone = True
 
+    msgmerge_options = ['-q', '--previous']
+    msguniq_options = ['--to-code=utf-8']
+    msgattrib_options = ['--no-obsolete']
+    xgettext_options = ['--from-code=UTF-8', '--add-comments=Translators']
+
     def handle_noargs(self, *args, **options):
         locale = options.get('locale')
         self.domain = options.get('domain')
@@ -217,8 +210,19 @@ class Command(NoArgsCommand):
         if options.get('use_default_ignore_patterns'):
             ignore_patterns += ['CVS', '.*', '*~', '*.pyc']
         self.ignore_patterns = list(set(ignore_patterns))
-        self.wrap = '--no-wrap' if options.get('no_wrap') else ''
-        self.location = '--no-location' if options.get('no_location') else ''
+
+        # Avoid messing with mutable class variables
+        if options.get('no_wrap'):
+            self.msgmerge_options = self.msgmerge_options[:] + ['--no-wrap']
+            self.msguniq_options = self.msguniq_options[:] + ['--no-wrap']
+            self.msgattrib_options = self.msgattrib_options[:] + ['--no-wrap']
+            self.xgettext_options = self.xgettext_options[:] + ['--no-wrap']
+        if options.get('no_location'):
+            self.msgmerge_options = self.msgmerge_options[:] + ['--no-location']
+            self.msguniq_options = self.msguniq_options[:] + ['--no-location']
+            self.msgattrib_options = self.msgattrib_options[:] + ['--no-location']
+            self.xgettext_options = self.xgettext_options[:] + ['--no-location']
+
         self.no_obsolete = options.get('no_obsolete')
         self.keep_pot = options.get('keep_pot')
 
@@ -307,12 +311,7 @@ class Command(NoArgsCommand):
             potfile = os.path.join(path, '%s.pot' % str(self.domain))
             if not os.path.exists(potfile):
                 continue
-            args = ['msguniq', '--to-code=utf-8']
-            if self.wrap:
-                args.append(self.wrap)
-            if self.location:
-                args.append(self.location)
-            args.append(potfile)
+            args = ['msguniq'] + self.msguniq_options + [potfile]
             msgs, errors, status = popen_wrapper(args)
             if errors:
                 if status != STATUS_OK:
@@ -389,12 +388,7 @@ class Command(NoArgsCommand):
         pofile = os.path.join(basedir, '%s.po' % str(self.domain))
 
         if os.path.exists(pofile):
-            args = ['msgmerge', '-q']
-            if self.wrap:
-                args.append(self.wrap)
-            if self.location:
-                args.append(self.location)
-            args.extend([pofile, potfile])
+            args = ['msgmerge'] + self.msgmerge_options + [pofile, potfile]
             msgs, errors, status = popen_wrapper(args)
             if errors:
                 if status != STATUS_OK:
@@ -413,12 +407,7 @@ class Command(NoArgsCommand):
             fp.write(msgs)
 
         if self.no_obsolete:
-            args = ['msgattrib', '-o', pofile, '--no-obsolete']
-            if self.wrap:
-                args.append(self.wrap)
-            if self.location:
-                args.append(self.location)
-            args.append(pofile)
+            args = ['msgattrib'] + self.msgattrib_options + ['-o', pofile, pofile]
             msgs, errors, status = popen_wrapper(args)
             if errors:
                 if status != STATUS_OK: