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From: bonnett@seismo.CSS.GOV (H. David Bonnett)
Newsgroups: comp.windows.x.motif
Subject: Re: Problem changing symbol pixmap for MessageBox widget
Message-ID: <49696@seismo.CSS.GOV>
Date: 11 Jun 91 18:53:44 GMT
Article-I.D.: seismo.49696
References: <187@atesysv.UUCP> <WEBB.91Jun7151121@firefox.cow.melco.co.jp> <191@atesysv.UUCP>
Sender: usenet@seismo.CSS.GOV
Organization: Center for Seismic Studies, Arlington, VA
Lines: 34


In article <191@atesysv.UUCP>, lanzo@wgate.UUCP (Mark Lanzo) writes:
|> In a prior article webb@cow.melco.co.jp (webb) wrote:
|>     
|>  >  I think that your problem could be your XtSetValues, and XtGetValues.
|>  >  These functions both take 3 parameters. Your program only passes 2
|>  >  parameters, the widget, and ARGS. You must also specify the number of
|>  >  args as the 3rd parameter.
|> 
|> Sigh.  I suppose I should have gone ahead and shown the macro def's.
|> As the old adage goes "assumption is the mother of all screwups." :-)
|> At any rate, my def's actually look like:
|> 
|>     #define 	MAX_WIDGET_ARGS	16
|>     #define	ARGS			WidgetArgs, WidgetArgCount
|>     #define	ARGLIST_RESET()		WidgetArgCount = 0
|>     #define	ARGLIST_ADD(tag,value) 					\
|> 		(XtSetArg(WidgetArgs[WidgetArgCount],tag,value),	\
|> 		WidgetArgCount++)
|>     Arg 	WidgetArgs[MAX_WIDGET_ARGS];
|>     Cardinal	WidgetArgCount;
|> 
|> So as you can see, the "ARGS" macro expands to two actual arguments.

Hmmm,
  I don't have the time to really check this out myself, but what will happen
with this upon exansion, given that XtSetArg is a macro itself that is evaluated
twice (see D. Young's book, p24 -or- OSF Motif Prog Guide p3.6) 
This may be part of the problem since you inc the counter inside the (nested)
macro calls.
Just a thought..
--
-dave bonnett-   Center for Seismic Studies;  Arlington, VA 
      bonnett@seismo.css.gov :  All standard disclaimers apply.