XtCheckSubclass(3)

NAME

       XtClass, XtSuperclass, XtIsSubclass, XtCheckSubclass, XtIsObject, XtIs-
       RectObj, XtIsWidget, XtIsComposite, XtIsConstraint, XtIsShell, XtIs-
       OverrideShell, XtIsWMShell, XtIsVendorShell, XtIsTransientShell, XtIs-
       TopLevelShell, XtIsApplicationShell, XtIsSessionShell - obtain and ver-
       ify a widget's class

SYNTAX

       WidgetClass XtClass(Widget w);

       WidgetClass XtSuperclass(Widget w);

       Boolean XtIsSubclass(Widget w, WidgetClass widget_class);

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

       Boolean XtIsObject(Widget w);

       Boolean XtIsRectObj(Widget w);

       Boolean XtIsWidget(Widget w);

       Boolean XtIsComposite(Widget w);

       Boolean XtIsConstraint(Widget w,

       Boolean XtIsShell(Widget w);

       Boolean XtIsOverrideShell(Widget w);

       Boolean XtIsWMShell(Widget w);

       Boolean XtIsVendorShell(Widget w);

       Boolean XtIsTransientShell(Widget w);

       Boolean XtIsTopLevelShell(Widget w);

       Boolean XtIsApplicationShell(Widget w);

       Boolean XtIsSessionShell(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 class. The wid-
       get's class can be any number of subclasses down the chain and need not
       be an immediate subclass of the specified class. Composite widgets that
       need to restrict the class of the items they contain can use XtIsSub-
       class to find out if a widget belongs to the desired class of objects.

       The XtCheckSubclass macro determines if the class of the specified wid-
       get 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.

       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, XtIs-
       TransientShell, XtIsTopLevelShell, XtIsApplicationShell, and XtIsSes-
       sionShell.

       The

SEE ALSO

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

X Version 11                      libXt 1.0.5                       XtClass(3)