Fix initialization of private variables in viewers

_table in TableView and _dataobj in PlotView were not initialized
in the constructor.

ginga/gw/PlotView.py

@@ -44,6 +44,8 @@ def __init__(self, logger=None, settings=None):
         else:
             self.logger = logging.Logger('PlotView')
 
+        self._dataobj = None
+
         # Create settings and set defaults
         if settings is None:
             settings = Settings.SettingGroup(logger=self.logger)

ginga/rv/Channel.py

@@ -592,15 +592,15 @@ def view_object(self, dataobj):
         # if there is only one viewer available, use it otherwise
         # pop-up a dialog and ask the user
         if len(viewers) == 1:
-            self._open_with_viewer(viewers[0], dataobj)
+            self.open_with_viewer(viewers[0], dataobj)
             return
 
         msg = ("Multiple viewers are available for this data object. "
                "Please select one.")
-        self.fv.gui_choose_viewer(msg, viewers, self._open_with_viewer,
+        self.fv.gui_choose_viewer(msg, viewers, self.open_with_viewer,
                                   dataobj)
 
-    def _open_with_viewer(self, vinfo, dataobj):
+    def open_with_viewer(self, vinfo, dataobj):
         # if we don't have this viewer type then install one in the channel
         if vinfo.name not in self.viewer_dict:
             self.fv.make_viewer(vinfo, self)
@@ -611,7 +611,8 @@ def _open_with_viewer(self, vinfo, dataobj):
         self.widget.set_index(idx)
 
         # and load the data
-        self.viewer.set_dataobj(dataobj)
+        if self.viewer.get_dataobj() is not dataobj:
+            self.viewer.set_dataobj(dataobj)
 
         obj_name = dataobj.get('name')
         if obj_name in self.image_index:

ginga/table/TableView.py

@@ -44,6 +44,8 @@ def __init__(self, logger=None, settings=None):
         else:
             self.logger = logging.Logger('TableViewBase')
 
+        self._table = None
+
         # Create settings and set defaults
         if settings is None:
             settings = Settings.SettingGroup(logger=self.logger)

ginga/util/viewer.py

@@ -10,7 +10,7 @@
 viewer_db = {}
 
 
-def register_viewer(vclass):
+def register_viewer(vclass, priority=0):
     """Register a channel viewer.
 
     Parameters
@@ -21,7 +21,7 @@ def register_viewer(vclass):
     global viewer_db
     viewer_db[vclass.vname] = Bunch.Bunch(name=vclass.vname,
                                           vclass=vclass,
-                                          priority=0)
+                                          priority=priority)
 
 
 def get_viewers(dataobj):