EditDomain: Skip attributes when describing old vars

Widget uses a dict for mapping of old variable descriptions to the new
ones. If an old variable contains values in its attributes dict, which
are not hashable, this makes description not hashable as well. This is
worked around by matching old variables by everything except attributes.

Fixes #1527

Author: astaric

Orange/widgets/data/oweditdomain.py

@@ -37,7 +37,7 @@ def get_qualified(module, name):
     return getattr(module, name)
 
 
-def variable_description(var):
+def variable_description(var, skip_attributes=False):
     """Return a variable descriptor.
 
     A descriptor is a hashable tuple which should uniquely define
@@ -46,18 +46,21 @@ def variable_description(var):
 
     """
     var_type = type(var)
+    attributes = ()
+    if not skip_attributes:
+        attributes = tuple(sorted(var.attributes.items()))
     if var.is_discrete:
         return (var_type.__module__,
                 var_type.__name__,
                 var.name,
                 (("values", tuple(var.values)),),
-                tuple(sorted(var.attributes.items())))
+                attributes)
     else:
         return (var_type.__module__,
                 var_type.__name__,
                 var.name,
                 (),
-                tuple(sorted(var.attributes.items())))
+                attributes)
 
 
 def variable_from_description(description, compute_value=None):
@@ -423,7 +426,7 @@ def reset_selected(self):
         ind = self.selected_var_index()
         if ind >= 0:
             var = self.input_vars[ind]
-            desc = variable_description(var)
+            desc = variable_description(var, skip_attributes=True)
             if desc in self.domain_change_hints:
                 del self.domain_change_hints[desc]
 
@@ -454,7 +457,7 @@ def _initialize(self):
     def _restore(self):
         # Restore the variable states from saved settings.
         def transform(var):
-            vdesc = variable_description(var)
+            vdesc = variable_description(var, skip_attributes=True)
             if vdesc in self.domain_change_hints:
                 return variable_from_description(
                     self.domain_change_hints[vdesc],
@@ -513,8 +516,8 @@ def _on_variable_changed(self):
 
 
         # Store the transformation hint.
-        self.domain_change_hints[variable_description(old_var)] = \
-                    variable_description(new_var)
+        old_var_desc = variable_description(old_var, skip_attributes=True)
+        self.domain_change_hints[old_var_desc] = variable_description(new_var)
 
         self._invalidate()