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XmtAssertWidgetClass(3)	   Library Functions Manual    XmtAssertWidgetClass(3)

NAME
       XmtAssertWidgetClass() -	verify the type	of a widget.

SYNOPSIS
       #include	<Xmt/Xmt.h>

       void XmtAssertWidgetClass(Widget	w, WidgetClass c, String procname)

ARGUMENTS
       INPUTS

	    w	   The widget to be checked.

	    c	   The desired widget class.

	    procname
		   An  identifying string to be	used in	the error message dis-
		   played if the widget	w is not of class c or a  subclass  of
		   it. This argument is	most useful when it is the name	of the
		   procedure that calls	XmtAssertWidgetClass().

DESCRIPTION
       XmtAssertWidgetClass()  calls XtIsSubclass() to verify that widget w is
       of class	c or is	a subclass of c.  If  so,  it  returns	and  takes  no
       action.	If  w  is  not of class	c or a subclass, then XmtAssertWidget-
       Class() prints an error message and calls the  function	abort()	 which
       will cause the application to dump core and exit.

USAGE
       XmtAssertWidgetClass()  is  an analog to	assert(). It is	used mainly by
       widget writers, but also	occasionally by	 application  programmers  who
       are  writing  a	function  that expects a widget	argument of a specific
       type. Many of the functions in  the  Xmt	 library  call	this  function
       internally.

       XmtAssertWidgetClass()  is  useful  during  the	process	of application
       development and debugging because it gives a very clear signal (a  mes-
       sage  and a core	dump with its associated stack trace) of when applica-
       tion code is calling a function with a bad  widget  argument.  Once  an
       application  is	debugged,  you	can  compile  your  code  (and the Xmt
       library)	with  the  -DNDEBUG  flag,  which  will	 cause	any  calls  to
       XmtAssertWidgetClass() to be removed by the C preprocessor.

SEE ALSO
       Chapter 8, Utility Functions,
       abort(),	assert(), XtIsSubclass().

Xmt				  Motif	Tools	       XmtAssertWidgetClass(3)

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