Path: utzoo!bnr-vpa!bnr-fos!bnr-public!schow
From: schow@bnr-public.uucp (Stanley Chow)
Newsgroups: comp.sys.amiga.tech
Subject: Why do you need metaphor? (Re: What should be learned from Unix
Summary: Use the real thing instead
Message-ID: <1417@bnr-fos.UUCP>
Date: 10 Aug 89 17:11:36 GMT
References: <7570@cbmvax.UUCP> <440@xdos.UUCP>
Sender: news@bnr-fos.UUCP
Reply-To: schow%BNR.CA.bitnet@relay.cs.net (Stanley Chow)
Organization: Bell-Northern Research, Ottawa, Canada
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In article <440@xdos.UUCP> doug@xdos.UUCP (Doug Merritt) writes:
> [discussion of how ps works on Unix.]                      In almost
>all other ways, Unix very consistently treats everything like a file.
					^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It is not clear (at least to me) that this is a good thing. Why do you
want everything to look like a file? A file has a very limiting structure.
Why would you want to force complicated data structure into a file? I think
appropiate use of linked data structure is entirely correct.

>
>And even with ps, Unix is nominally within the boundaries of that
>consistency, for it reads a symbol table from a file (/unix or /vmunix)
>to find the offsets in files of what it wants (/dev/mem and /dev/kmem).
>There is no poking directly around in memory.  I agree that this is a
>grey area and that it is inelegant on an absolute scale, but it is
>relatively elegant compared with the AmigaDOS method of directly accessing
>device/task data structures in your address space without any benefit
>of any consistency metaphor.
		    ^^^^^^^^

This is perhaps the key. I look on metaphor as an aid to learning something.
Once I know the subject, *it* becomes the metaphor for learning something
else. Why is it good to tie everything forever to a bad metaphor (files)?


>
>Both Unix and AmigaDOS would benefit from extensions that put the
>list of tasks (apparently) into a directory where they could be listed
>(and perhaps deleted, etc) using standard utilities. Unlike AmigaDOS, this
>ability *is* about to appear in a mainstream Unix: V5.4.

Again, my question: why should deleting a task be the same as deleting an 
entry from a directory? The code gets more complicated since the delete 
command now must know to call the delete-task routine. The user still has to
know that a task is involved so there is no hope of 'undo'.

Perhaps what you want is a 'consistant' interface where command names and
syntax for different commands follow a consistant convention. This is
very differnt from having the 'same' command do it in the same way.

>  [...]                     But the lesson from history (of Unix) that
>is most important, yet most widely disregarded, is that it *is* consistent,
>and the user *can* do all that stuff from the command line, and that
>all those utilities *do* behave well e.g. with piped input/output.

Not meaning to start another Unix flame war, but I think you mean that *you*
have found *a set* of utilities that fit well together with *your* style of
computer usage. The default set(s) of utilities from the variouse vendors
are by no means 'consistant'. Including all the freebies and bought S/W in
any description of 'consistant' is at best inconsistant.

>
>Unix has, compared with everything but the Smalltalk kernel, the greatest
>degree of consistency of application of its underlying metaphor, and that
>*inherently* makes it more powerful *overall* than any system with a
>lesser consistency. Don't even bother to criticize it until you've got
>a system that beats it in this respect. If you can set up message passing
>ports between tasks purely via the CLI in AmigaDOS, and if all standard
>utilities support this, then you've got something that might start making
>Unix look like a toy. But meanwhile, pretending that e.g. AmigaDos is
>*already* far better than Unix simply prevents learning from history.
>

I know almost nothing about any Unix-type kernal, so I cannot comment on the
kernal internals. I do, however have strong views about the consistancy
as seen by the *user*. In my view, Mac is more consistant than Amiga and
Amiga is more consistant than Unix.



Stanley Chow        BitNet:  schow@BNR.CA
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