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From: dkenny@atlantis.actrix.gen.nz (Des Kenny)
Subject: Re: what to use instead of TCL or PERL
Keywords: objects, components, inheritance, polymorphism
Distribution: inet
Message-ID: <DGy8uI.EEy@actrix.gen.nz>
Sender: Des Kenny
Summary: objects compared to "components" 
Organization: Actrix - Internet Services
Date: Tue, 24 Oct 1995 10:51:53 GMT
References: <43d0g9$aal@magus.cs.utah.edu> <MSFRIEDM.95Sep28105413@bingster.us.oracle.com> <CHENANDRE-0910951527080001@std32044.urich.edu> <462sdg$qqs@archangel.terraport.net>
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In article <462sdg$qqs@archangel.terraport.net>,
Red to Black Management <redblack@terraport.net> wrote:
> In article <CHENANDRE-0910951527080001@std32044.urich.edu>,
>    CHENANDRE@urvax.urich.edu (Andrew Shi-hwa Chen) wrote:
> >>  > Perl is used for CGI scripting and general tools work, and runs
> >>  > not just on Unix, but also VMS, MVS, MsDOS, NT, Amigas, Macs, and
> >>  > many other systems as well.  I would not say its use is restricted
> >>  > to Unix sysadmins, and if you haven't looked at it in the last five years,
> >>  > then you are probably working under some misunderstandings about the
> >>  > language.
>  
> 
>          I'm presently working with Appware from Novell, it works on macs and PC's.
>         If you purchase the CD version both Mac & PC are included. I find it better
>         then Visual Basic. You can also write custom objects called ALM's
>        for constant reuse. Worth to look at.
> 
>            Marcel


Are these Objects or "Components"? It is all a bit confusing.

I have seen one definition that makes a strong distinction:

Objects have inheritance and consequently polymorphism.

Components do not have inheritance and so no polymorphism.

I think some people call "Component" systems Object-Based systems in 
contrast to Object-Oriented Systems.

The word Component may be a better way to separate out the concepts of 
"objects" that belong to an explicit type hierarchy ( object-oriented 
inheritance) and "objects" that have no explicit type hierarchy ( 
encapsulated modules with no explicit ancestors).

Personally I prefer to have an explicit type hierarchy. Components are a 
sort of orphan concept, little waif modules that have no sense of 
belonging to the big picture of life.

Of course designing a type hierarchy is no overnight task and it is 
understandable that some may shy away from it at first blush and lean 
towards the apparently simpler component approach. Unfortunately, the 
benefits of the more simplistic approach are considerably less than the 
more advanced approach.


In the longer term it is a better choice to classify knowledge into a more
manageable , more  meaningfull structure than a collection of orphan 
components. All science eventually collects information into 
classification structures - it is the only way to comprehend and retrieve 
the rapidly growing body of knowledge. Type hierarchies are a sign that 
software is entering a new phase of maturity as a body of knowledge.



Cheers

 
Des Kenny

dkenny@swell.actrix.gen.nz






