NAME

XtCheckSubclass − verify an object’s class, if compiled with DEBUG defined. 

Synopsis

void XtCheckSubclass(object, object_class, message)

    Widget object;
    WidgetClass object_class;
    String message;

Inputs

objectSpecifies the object; may be of class Object or any subclass thereof. 

object_class
Specifies the widget class to test against; may be objectClass or any subclass thereof.

messageSpecifies the message to be displayed if object is not a subclass of object_class. 

Description

XtCheckSubclass() checks that object is of class object_class or a subclass.  If it is not, XtCheckSubclass() calls XtErrorMsg() passing message as the default message to be displayed.  XtErrorMsg() displays the message and terminates the application.  XtCheckSubclass() is implemented as a macro which only performs the check if compiled with the symbol DEBUG defined (i.e., if the C compiler is invoked with the flag
−DDEBUG).

Usage

XtCheckSubclass() is intended for use similar to the POSIX assert() macro while developing and debugging a widget or an application.  It should be used in all application and widget-internal functions that might inadvertently be passed an object of the wrong type.  Public functions exported by a widget should always check a widget’s class (not just when DEBUG is defined) using XtIsSubclass() or a related function because even if a widget is bug-free, an application programmer may still pass an object of the wrong type to the widget. 

See Also

XtClass(1), XtIsSubclass(1), XtSuperclass(1),
Core(3). 

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