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From: "Bart Schaefer" <schaefer@candle.brasslantern.com>
Message-Id: <960704085853.ZM5356@candle.brasslantern.com>
Date: Thu, 4 Jul 1996 08:58:51 -0700
In-Reply-To: Zoltan Hidvegi <hzoli@cs.elte.hu>
        "Re: cshjunkieparen bothers me (and always has)" (Jul  4,  3:14pm)
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To: Zoltan Hidvegi <hzoli@cs.elte.hu>
Subject: Re: cshjunkieparen bothers me (and always has)
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On Jul 4,  3:14pm, Zoltan Hidvegi wrote:
> Subject: Re: cshjunkieparen bothers me (and always has)
>
> > I *think* this is what happened:
> > 
> > Cshjunkieparen at one time affected whether
> > 
> > 	if [[ $TERM == xterm ]] then
> > 
> > would work.  This was the csh compatibility feature, even though it
> > wasn't precisely csh syntax.  I have no idea why "paren" was used in
> > the name of the option.
> 
> This syntax is really a ksh compatibility syntax.  But by a more general
> rure it is a POSIX compatibility syntax.

That may be, but there wasn't any such thing as `POSIX compatibility' (at
least within zsh) at the time that it was originally introduced as csh
compatibility.

> The biggest problem using braces instead of then ... fi is the following:
> 
> if (true)
> { echo yes; }
> 
> The patch I posted recently to the manual says that it is equivalent to
> 
> if (true)
> then
> 	echo yes
> fi
> 
> But that's not true since par_list parses a list as long as it is possible
> so the above is the same as
> 
> if (true) ; { echo yes; }
> 
> And now a then or an open brace should come after some semicolons.  I think
> csh junkies do not like that change.

I don't think csh junkies care one way or the other.  C junkies might,
but braces are not a command-grouping syntax in csh EXCEPT in exactly
one circumstance:

	#! /bin/csh
	if { something } then
	    echo something succeeded
	endif

I.e., in "if" (and possibly "while", I forget) statements, using braces
instead of parens is equivalent to:

	#! /bin/csh
	something
	if ( $status == 0 ) then
	    echo something succeeded
	endif

> if true {
> 	echo yes
> }
> 
> does not work either since { behaves like a reserved word (POSIX says that
> { and } should be reserved words).

That's equivalent to passing '{' as an argument to 'true', which is fine.
No problem with that either from a csh junkie standpoint; you can't omit
the parens in csh.  I note that this works:

	if { true } {
	    echo yes
	}

> To summarize this after Bart's patch the
> 
> if (foo)
> {
> 	...
> }
> 
> syntax will not work

But that in turn means that

	if [[ -f foo ]]
	{
	    ...
	}

has never worked, or at least hasn't worked for quite some time.  (Boy,
sometimes I wish my old machine with the 2.0.0 zsh on it hadn't died.)
In any case, I think this bit of consistency is worthwhile.


-- 
Bart Schaefer                             Brass Lantern Enterprises
http://www.well.com/user/barts            http://www.nbn.com/people/lantern

New male in /home/schaefer:
>N  2 Justin William Schaefer  Sat May 11 03:43  53/4040  "Happy Birthday"