XtClass(3Xt) XtClass(3Xt)
NAME
XtClass, XtSuperClass, XtIsSubclass, XtCheckSubclass,
XtIsComposite, XtIsManaged - 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(w, widget_class, message)
Widget w;
WidgetClass widget_class;
String message;
Boolean XtIsComposite(w)
Widget w;
Boolean XtIsManaged(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
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
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XtClass(3Xt) XtClass(3Xt)
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.
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 Programming Manual
Xlib Programming Manual
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