From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-0.0 required=3.0 tests=BAYES_20 autolearn=ham autolearn_force=no version=3.4.5-pre1 Date: 28 Sep 92 14:51:48 GMT From: agate!spool.mu.edu!caen!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!news .sei.cmu.edu!jjs@ucbvax.Berkeley.EDU (Jeffrey Stewart) Subject: Re: Using Global Variables Message-ID: <1992Sep28.145148.16757@sei.cmu.edu> List-Id: We are currently working with a design simulator project which will be running as either real-time or non real-time, depending on the site where it is installed. One of the engineering goals for this simulator was to be as run-time configurable as possible, given certain limitations of Ada. Our approach has been to incorporate some of the concepts of OODBs, where there is a central allocator of memory to which the objects subscribe, the objects then receive a pointer to their instance data. Objects are the only ones that know about their instance data. Other access to the instance data is done through the OODB services, which can provide pointer access to objects (for the record/play capability, with the items to be recorded being configurable at run-time), or through direct requests for getting or setting the state of a given object. Direct pointer access for record/play is required since some kind of look-up mechanism is needed to first find the objects, which is certainly not a "real-time" operation. The only run-time overhead during the actual simulation run involves pointer access, which we've found to be acceptable.