From: Byron Rakitzis <byron@rakitzis.com>
To: cks@hawkwind.utcs.toronto.edu, rc@hawkwind.utcs.toronto.edu
Subject: Re: New rc snapshot, includes "the equals hack"
Date: Mon, 21 Aug 2000 19:28:01 -0500 [thread overview]
Message-ID: <200008212328.QAA17096@rakitzis.com> (raw)
> Having read the messages to date and thought about the issue, I think
> that I agree with this. I prefer an rc where the rule I have to remember
> is 'quote ='s or get syntax errors', not '= will gobble the arguments
> on either side of it on a command line into one word' (or whatever the
> exact rule is). And slipups are far more evident and less mysterious
> with the first rule: I get a syntax error, which I can easily fix.
Well, the principle of "free carets" already establishes that there
can be some counterintuitive parsing:
; ~a
; a~
a~ not found
;
I guess the real problem is that = is an infix operator, and what's more
multiple local assignments are allowed:
a=foo b=bar cmd
This more than anything bollixed up any attempt to do the Right Thing
with yacc alone when I last puzzled over this (which was, mind you almost
10 years ago!).
And what is the right thing? I guess it's easy to say in English: if '='
does not appear in an assignment it should be subject to free careting.
This would be trivial to do in a recursive-descent parser which could
communicate with the lexer, I'm unsure about how to accomplish it
with yacc.
I think there is enough historical precedent about the use of unquoted
='s in shells that to be forced quote them is a truly annoying bug.
Byron.
next reply other threads:[~2000-08-22 20:13 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-08-22 0:28 Byron Rakitzis [this message]
2000-08-22 23:23 ` Chris Siebenmann
-- strict thread matches above, loose matches on Subject: below --
2000-08-23 1:03 Byron Rakitzis
2000-08-18 21:14 Bengt Kleberg
2000-08-15 20:25 smd
2000-08-15 14:32 smd
2000-08-15 22:51 ` Smarasderagd
2000-08-17 3:53 ` Decklin Foster
2000-08-21 23:21 ` Chris Siebenmann
2000-08-22 11:51 ` Carlo Strozzi
2000-08-17 10:49 ` Tim Goodwin
2000-08-15 7:28 Byron Rakitzis
2000-08-15 6:41 Byron Rakitzis
2000-08-11 14:01 Tim Goodwin
2000-08-15 2:21 ` Paul Haahr
2000-08-15 4:21 ` Gary Carvell
2000-08-15 14:52 ` Mark K. Gardner
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