XtIsComposite.3Xt.z(3Xt)



     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



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



          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
          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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