[meld/VersionControlRework: 96/123] vc._vc, vcview: Fix cross-tab command API presence checks

[Kai Willadsen <kaiw src gnome org>]

commit 23fc420ff85ca515728a01f581df13d388da2bf9
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sat Apr 11 09:46:55 2015 +1000

    vc._vc, vcview: Fix cross-tab command API presence checks
    
    This commit removes out empty interface-alike implementations for VC
    command API, and then uses simple attribute checking to handle the
    new-ish cross-tab command API.

 meld/vc/_vc.py |   21 ---------------------
 meld/vcview.py |   10 ++--------
 2 files changed, 2 insertions(+), 29 deletions(-)
---
diff --git a/meld/vc/_vc.py b/meld/vc/_vc.py
index a4eb50c..aa91f60 100644
--- a/meld/vc/_vc.py
+++ b/meld/vc/_vc.py
@@ -141,30 +141,9 @@ class Vc(object):
     def get_commit_message_prefill(self):
         return None
 
-    def commit(self, runner, files, message):
-        raise NotImplementedError()
-
-    def update(self, runner):
-        raise NotImplementedError()
-
-    def push(self, runner):
-        raise NotImplementedError()
-
-    def revert(self, runner, files):
-        raise NotImplementedError()
-
     def get_commits_to_push_summary(self):
         raise NotImplementedError()
 
-    def add(self, runner, files):
-        raise NotImplementedError()
-
-    def remove(self, runner, files):
-        raise NotImplementedError()
-
-    def resolve(self, runner, files):
-        raise NotImplementedError()
-
     def get_valid_actions(self, path_states):
         """Get the set of valid actions for paths with version states
 
diff --git a/meld/vcview.py b/meld/vcview.py
index b38ae5d..57dfbef 100644
--- a/meld/vcview.py
+++ b/meld/vcview.py
@@ -610,14 +610,8 @@ class VcView(melddoc.MeldDoc, gnomeglade.Component):
         yield workdir, r
 
     def has_command(self, command):
-        # Because of the way we've chosen to implement the newer command API,
-        # it's very very hard to determine whether a plugin implements a call
-        # at this point. We're using whether a plugin has been updated to the
-        # new API as a proxy for understanding these commands, since right now
-        # that happens to work... this is bad.
-        # FIXME: This is now even more broken than it was already
-        uses_new_api = hasattr(self.vc, 'update_actions_for_paths')
-        return uses_new_api and command in self.command_map
+        vc_command = self.command_map.get(command)
+        return vc_command and hasattr(self.vc, vc_command)
 
     def command(self, command, files):
         if not self.has_command(command):