[meld] Clean up the null VC module

[Kai Willadsen <kaiw src gnome org>]

commit 0c0c68ddee3febc28d7829dea2210b9231b28bfc
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun May 26 08:34:26 2013 +1000

    Clean up the null VC module

 meld/vc/_null.py |   62 +++++++++++++++++++++++++----------------------------
 meld/vcview.py   |    9 +++++--
 2 files changed, 35 insertions(+), 36 deletions(-)
---
diff --git a/meld/vc/_null.py b/meld/vc/_null.py
index 8ef801d..0f7fab5 100644
--- a/meld/vc/_null.py
+++ b/meld/vc/_null.py
@@ -1,40 +1,36 @@
-### Copyright (C) 2002-2005 Stephen Kennedy <stevek gnome org>
-
-### Redistribution and use in source and binary forms, with or without
-### modification, are permitted provided that the following conditions
-### are met:
-###
-### 1. Redistributions of source code must retain the above copyright
-###    notice, this list of conditions and the following disclaimer.
-### 2. Redistributions in binary form must reproduce the above copyright
-###    notice, this list of conditions and the following disclaimer in the
-###    documentation and/or other materials provided with the distribution.
-
-### THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
-### IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
-### OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
-### IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
-### INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
-### NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-### DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-### THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-### (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
-### THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from gettext import gettext as _
-
-from . import _vc
+# Copyright (C) 2002-2005 Stephen Kennedy <stevek gnome org>
+
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+from meld.vc import _vc
 
 
 class Vc(_vc.Vc):
 
-    CMD = "true"
-    NAME = _("None")
-    # Accept any directory
+    CMD = None
+    NAME = ""
     VC_DIR = "."
 
     def lookup_files(self, dirs, files, directory=None):
-        "files is array of (name, path). assume all files in same dir"
-        d = [_vc.Dir(x[1], x[0], _vc.STATE_NONE) for x in dirs]
-        f = [_vc.File(x[1], x[0], _vc.STATE_NONE) for x in files]
-        return d, f
+        dirs = [_vc.Dir(d[1], d[0], _vc.STATE_NONE) for d in dirs]
+        files = [_vc.File(f[1], f[0], _vc.STATE_NONE) for f in files]
+        return dirs, files
diff --git a/meld/vcview.py b/meld/vcview.py
index 36f104b..91441a1 100644
--- a/meld/vcview.py
+++ b/meld/vcview.py
@@ -408,6 +408,8 @@ class VcView(melddoc.MeldDoc, gnomeglade.Component):
             err_str = ""
 
             def vc_installed(cmd):
+                if not cmd:
+                    return True
                 try:
                     return not vc._vc.call(["which", cmd])
                 except OSError:
@@ -432,14 +434,15 @@ class VcView(melddoc.MeldDoc, gnomeglade.Component):
                 self.combobox_vcs.get_model().append(
                     [_("%s (%s)") % (avc.NAME, err_str), avc, False])
             else:
-                self.combobox_vcs.get_model().append([avc.NAME, avc, True])
+                name = avc.NAME or _("None")
+                self.combobox_vcs.get_model().append([name, avc, True])
 
         if not valid_vcs:
             # If we didn't get any valid vcs then fallback to null
             null_vcs = _null.Vc(vcs[0].location)
             vcs.append(null_vcs)
             self.combobox_vcs.get_model().insert(
-                0, [null_vcs.NAME, null_vcs, True])
+                0, [_("None"), null_vcs, True])
             default_active = 0
 
         if default_active == -1:
@@ -449,7 +452,7 @@ class VcView(melddoc.MeldDoc, gnomeglade.Component):
                 default_active = 0
 
         # If we only have the null VC, give a better error message.
-        if (len(vcs) == 1 and vcs[0].CMD == "true") or (len(valid_vcs) == 0):
+        if (len(vcs) == 1 and not vcs[0].CMD) or (len(valid_vcs) == 0):
             tooltip = _("No valid version control system found in this folder")
         elif len(vcs) == 1:
             tooltip = _("Only one version control system found in this folder")