NAME
XtClass, XtSuperclass, XtIsSubclass, XtCheckSubclass, XtIsObject, XtIsRectObj,
XtIsWidget, XtIsComposite, XtIsConstraint, XtIsShell, XtIsOverrideShell,
XtIsWMShell, XtIsVendorShell, XtIsTransientShell, XtIsTopLevelShell,
XtIsApplicationShell, XtIsSessionShell - obtain and verify 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
widget'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
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 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,
XtIsTransientShell,
XtIsTopLevelShell,
XtIsApplicationShell, and
XtIsSessionShell.
The
SEE ALSO
XtAppErrorMsg(3), XtDisplay(3)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface