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From: barmar@think.com (Barry Margolin)
Newsgroups: comp.os.misc
Subject: Re: What constitutes a good OS?
Message-ID: <1991Jan17.223526.2281@Think.COM>
Date: 17 Jan 91 22:35:26 GMT
References: <41907@nigel.ee.udel.edu> <5331@auspex.auspex.com> <42010@nigel.ee.udel.edu>
Sender: news@Think.COM
Organization: Thinking Machines Corporation, Cambridge MA, USA
Lines: 33

In article <42010@nigel.ee.udel.edu> new@ee.udel.edu (Darren New) writes:
>But if the filesystem supports keys, then your editors probably do also.

This appears to be the crux of your argument (with various replacements for
"editors").  I think this is an incorrect assumption to make.  Many OSes
have keyed files as a basic filesystem type, but they generally aren't used
for user-editable text files, or if they are the keys are ignored
(making them equivalent to non-keyed variable-length record files).

The problem with using general-purpose text editors to manipulate keyed
files is that the editor doesn't know the semantics of the keys.  A text or
program file might have line numbers in the keys, while the password file
might have the user names in the keys.  Many systems use keyed files as the
building block of databases, and then provide database query/update
applications that understand the semantics by looking at a data dictionary
or some database-specific attribute file.

This may not be a bad thing, by the way.  Why is it necessary that the
password file be editable with a general-purpose text editor?  If it were a
keyed file with binary record data it would be faster to parse (no scanning
for ':' characters) and harder to screw up (it would be updated by a
program that understands the format, rather than edited by hand).

By the way, to answer Guy's (I think) query about the existence of editors
that store unchanging line numbers, I can recall one such system: DTSS.
Its standard editor was basically the standard BASIC program input/update
user interface.  I remember editing entering and editing text formatter
files in this environment in the late 70's.
--
Barry Margolin, Thinking Machines Corp.

barmar@think.com
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