XtClass(3Xt)

NAME
       XtClass, XtSuperclass, XtIsSubclass, XtCheckSubclass,
       XtIsObject, XtIsRectObj, XtIsWidget, XtIsComposite, XtIs-
       Constraint, XtIsShell, XtIsOverrideShell, XtIsWMShell,
       XtIsVendorShell, XtIsTransientShell, XtIsTopLevelShell,
       XtIsApplicationShell, XtIsSessionShell - 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(widget, widget_class, message)
             Widget widget;
             WidgetClass widget_class;
             String message;

       Boolean XtIsObject(w)
             Widget w;

       Boolean XtIsRectObj(w)
             Widget w;

       Boolean XtIsWidget(w)
             Widget w;

       Boolean XtIsComposite(w)
             Widget w;

       Boolean XtIsConstraint(w)
             Widget w;

       Boolean XtIsShell(w)
             Widget w;

       Boolean XtIsOverrideShell(w)
             Widget w;

       Boolean XtIsWMShell(w)
             Widget w;

       Boolean XtIsVendorShell(w)
             Widget w;

       Boolean XtIsTransientShell(w)
             Widget w;

       Boolean XtIsTopLevelShell(w)
             Widget w;

       Boolean XtIsApplicationShell(w)
             Widget w;

       Boolean XtIsSessionShell(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 wid-
       get'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 spec-
       ified class. The widget's class can be any number of sub-
       classes down the chain and need not be an immediate sub-
       class of the specified 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 spec-
       ified widget class.  The widget can be any number of sub-
       classes down the chain and need not be an immediate sub-
       class 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; other-
       wise, it is defined as the empty string and generates no
       code.

       To test if a given widget belongs to a subclass of an
       Intrinsics-defined class, the Intrinsics defines macros or
       functions equivalent to XtIsSubclass for each of the

       built-in classes. These procedures are XtIsObject,
       XtIsRectObj, XtIsWidget, XtIsComposite, XtIsConstraint,
       XtIsShell, XtIsOverrideShell, XtIsWMShell,
       XtIsVendorShell, XtIsTransientShell, XtIsTopLevelShell,
       XtIsApplicationShell, and ZN XtIsSessionShell .

       The

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