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From: Dale Stanbrough <dale@goanna.cs.rmit.EDU.AU>
Subject: Ada/Motif problem...
Date: 1996/08/27
Message-ID: <4vupg6$ljf@goanna.cs.rmit.edu.au>#1/1
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organization: Royal Melbourne Institute of Technology
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newsgroups: comp.lang.ada
Date: 1996-08-27T00:00:00+00:00
List-Id: <comp.lang.ada>


Hi,

One of our students has run into problems writing a Motif routine.
The callback data is to be a string as follows..


Xt.Intrinsic.XtAddCallback(
                                 pb,
                                 Motif.xmstrdefs.XmNactivateCallback,
                                 hello_dialog_pkg.popup'access,
                                 "Hello World");
                                 

I've tried using unchecked_conversion from an access to all string
to XtPointer, but Gnat complains (quite rightly) about these pointer
types being of different sizes.

Any inspiration on how to pass Ada strings as callback data in Motif?

Here's the subprogram declaration...
                                 
procedure XtAddCallback(
                widget       : Xt.Intrinsic.Widget;
                callback_name: X.Strings.const_charp;
                callback     : XtCallbackProc;
                closure      : XtPointer);

Dale