ttk: fix LabeledScale and OptionMenu destroy() method (#3025) (#3030)

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.
(cherry picked from commit cd7e9c1b67d3d07ee03e0a79af2791c19031cecb)

diff --git a/Lib/tkinter/ttk.py b/Lib/tkinter/ttk.py
index 9cd0c2073a9f59b66f21ae82cfd9cfa840540101..2a3e1cec7015a003d2756599788cdbbbfbe404b0 100644 (file)
--- 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):
@@ -1647,5 +1648,8 @@ 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 (file)
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.