XtClass(3Xt)                X Version 11(Release 3)                XtClass(3Xt)


NAME
      XtClass, XtSuperClass, XtIsSubclass, XtCheckSubclass, XtIsComposite,
      XtIsManaged - obtain and verify a widget's class

SYNTAX
      WidgetClass XtClass(w)
            Widget w;

      WidgetClass XtSuperclass(w)
            Widget w;

      Boolean XtIsSubclass(w, widget_class)
            Widget w;
            WidgetClass widget_class;

      void XtCheckSubclass(w, widget_class, message)
            Widget w;
            WidgetClass widget_class;
            String message;

      Boolean XtIsComposite(w)
            Widget w;

      Boolean XtIsManaged(w)
             Widget w;

ARGUMENTS
      w         Specifies the widget.

      widget_class
                Specifies the widget class.

      message   Specifies the message that is to be used.

DESCRIPTION
      The XtClass function returns a pointer to the widget's class structure.

      The XtSuperclass function returns a pointer to the widget's superclass
      class structure.

      The XtIsSubclass function returns True if the class of the specified
      widget is equal to or is a subclass of the specified widget class.  The
      specified widget can be any number of subclasses down the chain and need
      not be an immediate subclass of the specified widget class.  Composite
      widgets that need to restrict the class of the items they contain can use
      XtIsSubclass to find out if a widget belongs to the desired class of
      objects.

      The XtCheckSubclass macro determines if the class of the specified widget
      is equal to or is a subclass of the specified widget class.  The widget
      can be any number of subclasses down the chain and need not be an
      immediate subclass of the specified widget class.  If the specified


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XtClass(3Xt)                X Version 11(Release 3)                XtClass(3Xt)


      widget is not a subclass, XtCheckSubclass constructs an error message
      from the supplied message, the widget's actual class, and the expected
      class and calls XtErrorMsg.  XtCheckSubclass should be used at the entry
      point of exported routines to ensure that the client has passed in a
      valid widget class for the exported operation.

      XtCheckSubclass is only executed when the widget has been compiled with
      the compiler symbol DEBUG defined; otherwise, it is defined as the empty
      string and generates no code.

      The XtIsComposite function is a convenience function that is equivalent
      to XtIsSubclass with compositeWidgetClass specified.

      The XtIsManaged macro (for widget programmers) or function (for
      application programmers) returns True if the specified child widget is
      managed or False if it is not.

SEE ALSO
      XtAppErrorMsg(3Xt), XtDisplay(3Xt)
      X Toolkit Intrinsics - C Language Interface
      Xlib - C Language X Interface

































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