hpux man page for destroy

destroy()																 destroy()

Name
  destroy - Object class method called when a widget is destroyed.

Synopsis
  typedef void (*XtWidgetProc)(Widget);
	 Widget w;

Inputs
  w	    Specifies the widget that is being destroyed.

Description
  The destroy() method is registered on the destroy field of the Object, RectObj, or Core class part structures.  It is invoked by XtDestroy-
  Widget() as part of the destruction process when any widget or object is destroyed, and should deallocate any memory or  resources  associ-
  ated with the part of the widget instance structure specific to this class.  It does not free the widget instance structure itself.

  The  destroy()  methods  of  a  widget  class  and all its superclasses are called in subclass-to-superclass order.  (Note that this is the
  reverse of the usual superclass-to-subclass chaining sequence.) The destroy() method of a widget class should deallocate  memory  or	other
  resources that were explicitly allocated by this class.  Any resource that was obtained from the resource database or passed in an argument
  list was not created by the widget and therefore should not be destroyed by it (unless the widget allocated memory  to  copy	the  resource
  value, in which case the memory must be freed).

  To reclaim memory, at least the following deallocations should be performed:

  o  Call XtFree() on dynamic storage allocated with XtCalloc(), XtMalloc(), etc.

  o  Call XFreePixmap() on pixmaps created with direct Xlib calls.

  o  Call XtReleaseGC() on GCs allocated with XtGetGC().

  o  Call XFreeGC() on GCs allocated with direct Xlib calls.

  o  Call XtRemoveEventHandler() on event handlers added with XtAddEventHandler().

  o  Call XtRemoveTimeOut() on timers created with XtAppAddTimeOut().

  o  Call XtDestroyWidget() for each child if the widget has children and is not a subclass of compositeWidgetClass.

  The  destroy() method is chained, so it cannot be inherited.	If a widget does not need to deallocate any storage, the destroy field in its
  widget class record should be NULL.

  See XtDestroyWidget(1) for details on the process of widget destruction.

Usage
  In general, a destroy() method will deallocate any resources allocated in the initialize() and set_values() methods.	This  often  includes
  GCs, pixmaps, and any copies that were made of string resources.

Example
  The  following  procedure is the destroy() method of the Xaw Label widget.  It frees the copy it made of its label string resource, deallo-
  cates two shared GCs, and frees the stipple pixmap it used to draw itself in insensitive mode.

     static void Destroy(w)
	 Widget w;
     {
	 LabelWidget lw = (LabelWidget)w;

	 XtFree( lw->label.label );
	 XtReleaseGC( w, lw->label.normal_GC );
	 XtReleaseGC( w, lw->label.gray_GC);
	 XmuReleaseStippledPixmap( XtScreen(w), lw->label.stipple );
     }

See Also
  XtDestroyWidget(1),
  Core(3),
  Constraint destroy(4), initialize(4), set_values(4).

Xt - Intrinsics Methods 														 destroy()