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From: davest@lumiere.UUCP (Dave Stewart)
Newsgroups: net.unix,net.unix-wizards
Subject: Re: Bourne shell modifications, past and future
Message-ID: <1453@lumiere.UUCP>
Date: Wed, 27-Nov-85 11:49:56 EST
Article-I.D.: lumiere.1453
Posted: Wed Nov 27 11:49:56 1985
Date-Received: Fri, 29-Nov-85 07:56:55 EST
References: <1943@gatech.CSNET> <10@druri.UUCP> <21@pixdoc.UUCP> <3@bbncc5.UUCP> <161@nitrex.UUCP> <122@rexago1.UUCP> <847@whuxl.UUCP>
Reply-To: davest@lumiere.UUCP (Dave Stewart)
Organization: Tektronix, Beaverton OR
Lines: 38
Xref: watmath net.unix:6409 net.unix-wizards:15885

In article <847@whuxl.UUCP> mike@whuxl.UUCP (BALDWIN) writes:
>I think providing *both* aliasing and functions is a misfeature!  Why have
>two inconsistent ways of doing the same thing???
> ...
>Back to my first point:  please don't implement something 2 or 3 times
>in different ways!  Functions subsume aliases very nicely, so chuck
>aliases!

	The same thing could be said for the "for" "while-do" and "do-while"
constructs in C.  It can be proven that any of these can be subsumed
by one of them - so why have all THREE ways of doing the same thing?  Well,
history for one thing and programmer convenience for another.  That's why
you provide both aliases and functions - aliases have a history (excuse the
pun) in csh.  Having both is more convenient.

	In ksh, aliases take on other roles as well: tracked aliases
are as a replacement for the command hashing of csh.  There are also a
handful of aliases predefined upon shell invocation which (in a sense)
provide the user with more things that look like builtins without
actually adding more builtins.

	I think most people who have both aliases and functions available
use aliases as command-name macros and shell functions like programming
language functions.  Well, the analogy isn't perfect, since one also
has shell scripts to act as "functions", but I believe the concept is
transferable.  Do I want to chuck out macros because I have functions
available?  Heck no.

	Finally, there is a line in the ksh intro paper that reads, "Functions
are more general than aliases but also more costly."  Well, I guess
that's implementation-dependant, but intuition would tend to support
this, even when one considers that functions usually take up more text
chars before being read.

-- 
David C. Stewart                          uucp:    tektronix!davest
Unix Systems Support Group                csnet:   davest@TEKTRONIX
Tektronix, Inc.                           phone:   (503) 627-5418