[meld] meldapp: Behaviour fix for exiting on parser errors (bgo#730392)

[Kai Willadsen <kaiw src gnome org>]

commit bfb60ae63792d67a0f1cedf0c60186f3f015ad63
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Tue May 20 06:54:50 2014 +1000

    meldapp: Behaviour fix for exiting on parser errors (bgo#730392)
    
    Because of the remote instance handling weirdness with the OptionParser
    handling, we need to try and handle parser errors in multiple places,
    with different handling for internal OptionParser error calls vs. our
    own error handling.

 meld/meldapp.py |   58 ++++++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 45 insertions(+), 13 deletions(-)
---
diff --git a/meld/meldapp.py b/meld/meldapp.py
index 3b46580..1069835 100644
--- a/meld/meldapp.py
+++ b/meld/meldapp.py
@@ -180,9 +180,10 @@ class MeldApp(Gtk.Application):
                 self.command_line = command_line
                 self.should_exit = False
                 self.output = StringIO.StringIO()
+                self.exit_status = 0
                 optparse.OptionParser.__init__(self, *args, **kwargs)
 
-            def exit(self, *args):
+            def exit(self, status=0, msg=None):
                 self.should_exit = True
                 # FIXME: This is... let's say... an unsupported method. Let's
                 # be circumspect about the likelihood of this working.
@@ -191,6 +192,7 @@ class MeldApp(Gtk.Application):
                         self.command_line, self.output.getvalue())
                 except:
                     print(self.output.getvalue())
+                self.exit_status = status
 
             def print_usage(self, file=None):
                 if self.usage:
@@ -203,6 +205,16 @@ class MeldApp(Gtk.Application):
             def print_help(self, file=None):
                 print(self.format_help(), file=self.output)
 
+            def error(self, msg):
+                self.local_error(msg)
+                raise ValueError()
+
+            def local_error(self, msg):
+                self.print_usage()
+                error_string = _("Error: %s\n") % msg
+                print(error_string, file=self.output)
+                self.exit(2)
+
         parser = GLibFriendlyOptionParser(
             command_line=command_line,
             usage=usage,
@@ -236,22 +248,34 @@ class MeldApp(Gtk.Application):
             dest="diff", default=[],
             help=_("Create a diff tab for the supplied files or folders"))
 
+        def cleanup():
+            if not command_line.get_is_remote():
+                self.quit()
+            parser.command_line = None
+
         rawargs = command_line.get_arguments()[1:]
-        options, args = parser.parse_args(rawargs)
-        parser.command_line = None
+        try:
+            options, args = parser.parse_args(rawargs)
+        except ValueError:
+            # Thrown to avert further parsing when we've hit an error, because
+            # of our weird when-to-exit issues.
+            pass
+
         if parser.should_exit:
-            if command_line.get_is_remote():
-                return 0
-            else:
-                self.quit()
+            cleanup()
+            return parser.exit_status
 
         if len(args) > 3:
-            parser.error(_("too many arguments (wanted 0-3, got %d)") %
-                         len(args))
+            parser.local_error(_("too many arguments (wanted 0-3, got %d)") %
+                               len(args))
         elif options.auto_merge and len(args) < 3:
-            parser.error(_("can't auto-merge less than 3 files"))
+            parser.local_error(_("can't auto-merge less than 3 files"))
         elif options.auto_merge and any([os.path.isdir(f) for f in args]):
-            parser.error(_("can't auto-merge directories"))
+            parser.local_error(_("can't auto-merge directories"))
+
+        if parser.should_exit:
+            cleanup()
+            return parser.exit_status
 
         if options.comparison_file or (len(args) == 1 and
                                        args[0].endswith(".meldcmp")):
@@ -261,7 +285,10 @@ class MeldApp(Gtk.Application):
             try:
                 tab = self.get_meld_window().append_recent(gio_file.get_uri())
             except (IOError, ValueError):
-                parser.error(_("Error reading saved comparison file"))
+                parser.local_error(_("Error reading saved comparison file"))
+            if parser.should_exit:
+                cleanup()
+                return parser.exit_status
             return tab
 
         error = None
@@ -284,10 +311,15 @@ class MeldApp(Gtk.Application):
 
         if error:
             if not self.get_meld_window().has_pages():
-                parser.error(error)
+                parser.local_error(error)
             else:
                 print(error)
 
+        if parser.should_exit:
+            cleanup()
+            return parser.exit_status
+
+        parser.command_line = None
         return tab if len(comparisons) == 1 else None