hpux man page for constrainta

Constraint destroy()													      Constraint destroy()

Name
  Constraint destroy - Constraint class method for freeing resources associated with a child's constraint record.

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

Inputs
  w	    Specifies the widget being destroyed.

Description
  The  Constraint  destroy()  method  is registered on the destroy field of the Constraint class part structure (which is not the same as the
  destroy field of the Object or Core class part structure).  It is called by XtDestroyWidget() when the child	of  a  constraint  widget  is
  destroyed, and should deallocate any memory or resources associated with the part of the constraint record of w that is owned by the class.
  It should not deallocate the constraint record itself.

  This method is similar to the Object destroy() method.  The Constraint destroy() methods of a widget class and its superclasses are  called
  in  subclass-to-superclass  order, starting at the class of the parent of w, and ending at the Constraint class.  Therefore, the Constraint
  destroy() method should deallocate only memory and resources associated with the part of the constraint record specific to its  class,  and
  not the memory or resources allocated by any of its superclasses.

  The  Constraint  destroy() method is chained, and so cannot be inherited.  If a constraint widget does not need to deallocate any memory or
  resources associated with its constraint part structure, the destroy field in its Constraint class part record can be NULL.

  See destroy(4) for more information about what should be freed and what should not.  See XtDestroyWidget(1) for details on the  widget  and
  object destruction process.

Example
  The  following  procedure is the Constraint destroy() method of the Xaw Tree widget.	Note that it uses a macro (defined below) to cast the
  specified widget's constraint field appropriately, and calls XtParent() on the specified widget to obtain the Tree widget itself.

  This procedure is a somewhat unusual example, because it does not directly call XtFree(), XtReleaseGC(), or similar functions on fields  of
  the  constraint  record.   The  constraint records of the Tree class are linked in a tree structure, and this procedure is used to remove a
  node from that tree.	This might have been more appropriate in the delete_child() method instead.

     static void ConstraintDestroy (w)
	 Widget w;
     {
	 TreeConstraints tc = TREE_CONSTRAINT(w);
	 TreeWidget tw = (TreeWidget) XtParent(w);
	 int i;

	 /*
	  * Remove the widget from its parent's sub-nodes list and
	  * make all this widget's sub-nodes sub-nodes of the parent.
	  */

	 if (tw->tree.tree_root == w) {
	     if (tc->tree.n_children > 0)
	       tw->tree.tree_root = tc->tree.children[0];
	     else
	       tw->tree.tree_root = NULL;
	 }

	 delete_node (tc->tree.parent, (Widget) w);
	 for (i = 0; i< tc->tree.n_children; i++)
	   insert_node (tc->tree.parent, tc->tree.children[i]);

	 layout_tree ((TreeWidget) (w->core.parent), FALSE);
     }

  The useful TREE_CONSTRAINTS macro is defined as follows:

     #define TREE_CONSTRAINT(w) ((TreeConstraints)((w)->core.constraints))

See Also
  XtDestroyWidget(1),
  Constraint(3), Core(3).

Xt - Intrinsics Methods 												      Constraint destroy()