XtClass(3Xt)                  X11 SDE 5.4R3.00                  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, widgetclass)
             Widget w;
             WidgetClass widgetclass;

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

       Boolean XtIsComposite(w)
             Widget w;

       Boolean XtIsManaged(w)
              Widget w;

ARGUMENTS
       w         Specifies the widget.

       widgetclass
                 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 widget is not a subclass, XtCheckSubclass constructs an



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XtClass(3Xt)                  X11 SDE 5.4R3.00                  XtClass(3Xt)


       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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