Path: utzoo!attcan!uunet!husc6!bloom-beacon!ATHENA.MIT.EDU!swick
From: swick@ATHENA.MIT.EDU (Ralph R. Swick)
Newsgroups: comp.windows.x
Subject: Re: Widget writing: XtGetValues()
Message-ID: <8808051648.AA06425@LYRE.MIT.EDU>
Date: 5 Aug 88 16:47:58 GMT
References: <4859@pasteur.Berkeley.EDU>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: DEC/MIT Project Athena
Lines: 25

I have to infer a lot from your description of your problem, as it's
not clear to me whether you are using an existing widget (which may
have bugs) or writing your own widget.

I suspect the problem you are having is one that has confused many people.
Resources of representation type XtRString are typedef'd as String;
that is, char*.  Thus the value of the resource is the pointer, not
the contents of the string.  When you do an XtGetValues, you'll get
the pointer; no copying is done.  So you really want something like:

    Arg arg;
    char *buf;

    XtSetArg(arg, XtNstring, &buf);
    XtGetValues(widget, &arg, ONE);

So your diagnosis of the problem was correct.  I can't guess why
you may be having similar problems with other widget resources,
without knowing the widgets involved.  It is a common error to
forget that XtGetValues requires the arglist to contain pointer(s)
to the destination(s); the returned values are not stored into
the arglist directly.

If you happen to be using Xaw(AsciiString), then you're going to lose
anyway, as GetValues(XtNstring) is broken in that widget.