[meld] Make our state saving an enum, for both sanity and better debugging

[Kai Willadsen <kaiw src gnome org>]

commit c2b29ade6acabd882055c7e14f1289a92cad5a02
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Feb 18 07:51:34 2018 +1000

    Make our state saving an enum, for both sanity and better debugging
    
    This way at least we get meaningful names when debugging these state
    transitions. Also, it's better in every way.
    
    I've used an IntEnum here just so that I keep the state-changed signal
    signature, though there's no reason that needs to remain the same,
    really.

 meld/filediff.py   | 13 ++++++-------
 meld/melddoc.py    | 10 +++++++---
 meld/meldwindow.py |  4 ++--
 3 files changed, 15 insertions(+), 12 deletions(-)
---
diff --git a/meld/filediff.py b/meld/filediff.py
index b3a82563..b87148eb 100644
--- a/meld/filediff.py
+++ b/meld/filediff.py
@@ -35,8 +35,7 @@ from meld.matchers.helpers import CachedSequenceMatcher
 from meld.matchers.merge import Merger
 from meld.meldbuffer import (
     BufferDeletionAction, BufferInsertionAction, BufferLines)
-from meld.melddoc import (
-    MeldDoc, STATE_CLOSING, STATE_NORMAL, STATE_SAVING_ERROR)
+from meld.melddoc import ComparisonState, MeldDoc
 from meld.patchdialog import PatchDialog
 from meld.recent import RecentType
 from meld.settings import bind_settings, meldsettings
@@ -880,12 +879,12 @@ class FileDiff(MeldDoc, Component):
                     # idle loop; it might never happen.
                     parent.command('resolve', [conflict_file], sync=True)
         elif response == Gtk.ResponseType.CANCEL:
-            self.state = STATE_NORMAL
+            self.state = ComparisonState.Normal
 
         return response
 
     def on_delete_event(self):
-        self.state = STATE_CLOSING
+        self.state = ComparisonState.Closing
         response = self.check_save_modified()
         if response == Gtk.ResponseType.OK:
             for h in self.settings_handlers:
@@ -1636,7 +1635,7 @@ class FileDiff(MeldDoc, Component):
                 secondary=_("Couldn’t save file due to:\n%s") % (
                     GLib.markup_escape_text(str(err))),
             )
-            self.state = STATE_SAVING_ERROR
+            self.state = ComparisonState.SavingError
             return
 
         self.emit('file-changed', gfile.get_path())
@@ -1645,11 +1644,11 @@ class FileDiff(MeldDoc, Component):
         if pane == 1 and self.num_panes == 3:
             self.meta['middle_saved'] = True
 
-        if (self.state == STATE_CLOSING and
+        if (self.state == ComparisonState.Closing and
                 not any(b.get_modified() for b in self.textbuffer)):
             self.on_delete_event()
         else:
-            self.state = STATE_NORMAL
+            self.state = ComparisonState.Normal
 
     def make_patch(self, *extra):
         dialog = PatchDialog(self)
diff --git a/meld/melddoc.py b/meld/melddoc.py
index cbca6e09..1155f826 100644
--- a/meld/melddoc.py
+++ b/meld/melddoc.py
@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import enum
 import logging
 import pipes
 import shlex
@@ -50,8 +51,11 @@ def make_custom_editor_command(path, line=0):
     return shlex.split(cmd)
 
 
-# TODO: Consider use-cases for states in gedit-enum-types.c
-STATE_NORMAL, STATE_CLOSING, STATE_SAVING_ERROR, NUM_STATES = range(4)
+class ComparisonState(enum.IntEnum):
+    # TODO: Consider use-cases for states in gedit-enum-types.c
+    Normal = 0
+    Closing = 1
+    SavingError = 2
 
 
 class LabeledObjectMixin(GObject.GObject):
@@ -93,7 +97,7 @@ class MeldDoc(LabeledObjectMixin, GObject.GObject):
         self.scheduler = FifoScheduler()
         self.num_panes = 0
         self.main_actiongroup = None
-        self._state = STATE_NORMAL
+        self._state = ComparisonState.Normal
 
     @property
     def state(self):
diff --git a/meld/meldwindow.py b/meld/meldwindow.py
index 72e5e28c..e941c773 100644
--- a/meld/meldwindow.py
+++ b/meld/meldwindow.py
@@ -24,7 +24,7 @@ from meld.conf import _
 from meld.dirdiff import DirDiff
 from meld.filediff import FileDiff
 from meld.filemerge import FileMerge
-from meld.melddoc import MeldDoc, STATE_CLOSING
+from meld.melddoc import ComparisonState, MeldDoc
 from meld.newdifftab import NewDiffTab
 from meld.recent import recent_comparisons, RecentType
 from meld.settings import interface_settings, settings
@@ -515,7 +515,7 @@ class MeldWindow(Component):
                     self.widget.emit('destroy')
 
     def on_page_state_changed(self, page, old_state, new_state):
-        if self.should_close and old_state == STATE_CLOSING:
+        if self.should_close and old_state == ComparisonState.Closing:
             # Cancel closing if one of our tabs does
             self.should_close = False