XtClass(3Xt)XtClass(3Xt)NAME
XtClass, XtSuperclass, XtIsSubclass, XtCheckSubclass, XtIsObject, XtIs‐
RectObj, XtIsWidget, XtIsComposite, XtIsConstraint, XtIsShell, XtI‐
sOverrideShell, XtIsWMShell, XtIsVendorShell, XtIsTransientShell,
XtIsTopLevelShell, XtIsApplicationShell, XtIsSessionShell - obtain and
verify a widget's class
SYNOPSIS
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
Specifies the widget. Specifies the widget class. Specifies the mes‐
sage 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, XtIsTran‐
sientShell, XtIsTopLevelShell, XtIsApplicationShell, and XtIsSession‐
Shell.
SEE ALSOXtAppErrorMsg(3Xt), XtDisplay(3Xt)
X Toolkit Intrinsics -- C Language Interface
Xlib -- C Language X Interface
XtClass(3Xt)
