Remove early attribute clearing in destroy

Removing those attributes could lead to errors where in the code we expect to
have those attributes.
It is better to leave them and let the garbage collector detect them.

review3251002

tryton/gui/window/form.py

@@ -186,10 +186,6 @@ class Form(SignalEvent, TabContent):
 
     def destroy(self):
         self.screen.destroy()
-        self.screen = None
-        self.widget = None
-        #self.scrolledwindow.destroy()
-        #self.scrolledwindow = None
 
     def sel_ids_get(self):
         return self.screen.sel_ids_get()

tryton/gui/window/view_form/model/group.py

@@ -416,7 +416,6 @@ class Group(SignalEvent, list):
                 pass
         self.clear()
         super(Group, self).destroy()
-        self.parent = None
 
     def get_by_path(self, path):
         'return record by path'

tryton/gui/window/view_form/model/record.py

@@ -622,8 +622,5 @@ class Record(SignalEvent):
             if hasattr(v, 'destroy'):
                 v.destroy()
         super(Record, self).destroy()
-        self.group = None
-        self.value = None
-        self.next = None
         self.destroyed = True
         pool.remove(self)

tryton/gui/window/view_form/screen/screen.py

@@ -324,11 +324,6 @@ class Screen(SignalEvent):
         for view in self.views:
             view.destroy()
         super(Screen, self).destroy()
-        self.parent = None
-        self.__group = None
-        self.__current_record = None
-        self.screen_container = None
-        self.widget = None
 
     def default_row_activate(self):
         if (self.current_view.view_type == 'tree' and

tryton/gui/window/view_form/view/calendar_gtk/calendar_.py

@@ -21,9 +21,6 @@ class Calendar_(goocalendar.Calendar):
         self.event_store = event_store
         self.current_domain_period = self.get_displayed_period()
 
-    def destroy(self):
-        super(Calendar_, self).destroy()
-
     def set_default_date(self, record, selected_date):
         attrs = common.node_attributes(self.root_node)
         dtstart = attrs.get('dtstart')

tryton/gui/window/view_form/view/form.py

@@ -64,10 +64,6 @@ class ViewForm(ParserView):
                 widget.destroy()
             del self.widgets[widget_name]
         self.widget.destroy()
-        self.widget = None
-        self.widgets = None
-        self.screen = None
-        self.state_widgets = None
 
     def cancel(self):
         for widgets in self.widgets.itervalues():

tryton/gui/window/view_form/view/form_gtk/many2many.py

@@ -130,8 +130,6 @@ class Many2Many(WidgetInterface):
 
     def destroy(self):
         self.screen.destroy()
-        self.widget.destroy()
-        del self.widget
 
     def color_set(self, name):
         super(Many2Many, self).color_set(name)

tryton/gui/window/view_form/view/graph.py

@@ -21,9 +21,6 @@ class ViewGraph(ParserView):
         for widget in self.widgets.keys():
             self.widgets[widget].destroy()
             del self.widgets[widget]
-        self.widget = None
-        self.screen = None
-        self.state_widgets = None
 
     def cancel(self):
         pass

tryton/gui/window/view_form/view/list.py

@@ -727,9 +727,6 @@ class ViewList(ParserView):
     def destroy(self):
         self.save_width_height()
         self.widget_tree.destroy()
-        self.screen = None
-        self.widget_tree = None
-        self.widget = None
 
     def __sig_switch(self, treeview, path, column):
         if column._type == 'button':

tryton/gui/window/wizard.py

@@ -119,8 +119,6 @@ class Wizard(object):
     def destroy(self):
         if self.screen:
             self.screen.destroy()
-            del self.screen
-        del self.widget
 
     def end(self):
         try: