ttk: fix LabeledScale and OptionMenu destroy() method (#3025)

bpo-31135: Call the parent destroy() method even if the used
attribute doesn't exist.

The LabeledScale.destroy() method now also explicitly clears label
and scale attributes to help the garbage collector to destroy all
widgets.

2 files changed, 12 insertions, 4 deletions

diff --git a/Lib/tkinter/ttk.py b/Lib/tkinter/ttk.py
index 3ecc004..e1a965e 100644
--- a/Lib/tkinter/ttk.py
+++ b/Lib/tkinter/ttk.py
@@ -1543,11 +1543,12 @@ class LabeledScale(Frame):
         try:
             self._variable.trace_vdelete('w', self.__tracecb)
         except AttributeError:
-            # widget has been destroyed already
             pass
         else:
             del self._variable
-            Frame.destroy(self)
+        super().destroy()
+        self.label = None
+        self.scale = None
 
 
     def _adjust(self, *args):
@@ -1644,5 +1645,8 @@ class OptionMenu(Menubutton):
 
     def destroy(self):
         """Destroy this widget and its associated variable."""
-        del self._variable
-        Menubutton.destroy(self)
+        try:
+            del self._variable
+        except AttributeError:
+            pass
+        super().destroy()
diff --git a/Misc/NEWS.d/next/Library/2017-08-08-14-44-37.bpo-31135.HH94xR.rst b/Misc/NEWS.d/next/Library/2017-08-08-14-44-37.bpo-31135.HH94xR.rst
new file mode 100644
index 0000000..60068fb
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-08-08-14-44-37.bpo-31135.HH94xR.rst
@@ -0,0 +1,4 @@
+ttk: fix the destroy() method of LabeledScale and OptionMenu classes.
+Call the parent destroy() method even if the used attribute doesn't
+exist. The LabeledScale.destroy() method now also explicitly clears label and
+scale attributes to help the garbage collector to destroy all widgets.