Subject: Re: e-mail discussion on review report
From: Wolfram Putzke Roeming (Putzke@offis.de)
Date: Fri Mar 17 2000 - 03:34:54 PST
The intention of my last posting was not to promote Objective VHDL
or the VISTA approach. In previous postings to the reflector the questions
about usefulness of entity objects and polymorphism on entity objects
had been raised. Outside the approaches which are discussed in the
study group the published work on the VISTA approach addresses
exactly these questions. Further the VISTA people not only say
entity objects are useful (or not). They also tried to quantify the
the benefits they observed.
I just want to remind to this work which I think can be very valuable
to the group.
Peter Ashenden wrote:
> Wolfram Putzke Roeming wrote:
> >
> > I'd like to remember to the VISTA Technologies OO-VHDL proposal.They provide
> > polymorphism for entity objects. In their paper in IEEE
> > Computer 10/95 they claim to have modelled some "larger" examples
> > with their entity object approach. The paper also contains some quantification
> > on the benefits for reuse etc. that they have measured.
>
> The Vista OOVHDL approach was to define methods in entities, similar to
> the way in which you did in Objective VHDL. In inherited architectures,
> they allowed overriding of methods. This is different from inheriting
> structure and implicit connection of processes to signals via drivers.
I don't understand the difference you mention exactly. As far as I understoodthe
VISTA proposal both, VISTA and Objective VHDL provide inheritance of
ports, methods, and processes.
A derived entity object can add ports but is not allowed to redefine an inherited
port (Objective VHDL & VISTA). Further, both approaches allow
to inherit methods or to redefine them with inheritance. Both
approaches allow to derive architectures. A derived architecture inherits
the processes of the parent architecture and is allowed to redefine them
if the processes are labeled.
However, the VISTA LRM is not very detailed in the description of
process inheritance and redefinition.
Cheers,
Wolfram
-- ____________________________________________________ Dipl. inf. Wolfram Putzke-Roeming OFFIS Embedded Systems Escherweg 2 - 26121 Oldenburg - Germany Fon: +49 4 41 798- 2160 - Fax: +49 4 41 798- 2155 E-Mail: putzke@offis.de - URL: http://www.offis.de
This archive was generated by hypermail 2b28 : Fri Mar 17 2000 - 03:38:55 PST