Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!bcm!rice!uw-beaver!cornell!rcbc
From: rcbc@cs.cornell.edu (Robert Cooper)
Newsgroups: comp.sys.isis
Subject: Re: isis and C++
Message-ID: <51494@cornell.UUCP>
Date: 1 Feb 91 20:45:08 GMT
References: <1991Feb1.151157.17332@noose.ecn.purdue.edu>
Sender: nobody@cornell.UUCP
Reply-To: rcbc@cs.cornell.edu (Robert Cooper)
Organization: Cornell University Computer Science Department
Lines: 32
In-reply-to: rembold@rainbow.ecn.purdue.edu (Bernhard F Rembold)

In article <1991Feb1.151157.17332@noose.ecn.purdue.edu>, rembold@rainbow (Bernhard F Rembold) writes:
>
>I am trying to use ISIS with C++ and have gotten somewhat confused with
>the use of basic functions such as 'isis_entry', 'isis_task' etc. Going
>through the declarations in the 'isis.h' file has given me some insight
>but has not helped me set up a working client-server model.
>I would be grateful if someone could post or e-mail me a set of simple
>example programs (i.e. client & server) in C++ similar to the timeclock 
>example described in the ISIS reference manual.
>
>Thanks in advance, 
>  Bernhard 
>

The main hassle using Isis from C++ is the issue of callback functions.
It is difficult to pass a C++ member-function as a callback to many 
Isis routines that want callbacks, such as isis_entry, t_fork,
pg_monitor etc., because its difficult to pass in the object to
which the member-function belongs as the "hidden" argument
to the member-function. 

The general way to get around this problem is to write regular C
wrapper functions that call the appropriate C++ member functions.
This loses some of the generality of C++, but it works. 

If I get time I'll post an example tiny program to illustrate this,
or one of the C++ Isis users out there might want to give an example.

"Eventually" we will do a better C++ interface on top of the C Isis
interface.

                          -- Robert Cooper