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From: "S. Cowles" <scowles@earthlink.net>
Reply-To: scowles@earthlink.net
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To: zsh users <zsh-users@sunsite.dk>
Subject: Re: help with dereferencing variables
Date: Sat, 14 Feb 2004 20:12:32 -0800
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References: <200402140959.24015.scowles@earthlink.net> <1040214212400.ZM15293@candle.brasslantern.com>
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Many thanks; that was the info I was missing.  One small aesthetics prefere=
nce=20
following up on your suggestion and I'm away (does not preserve newlines in=
=20
the array element assignments):

eval ${key}\=3D\( ${(P)val} \)

cheers.


On Saturday 14 February 2004 13:24, Bart Schaefer wrote:
> On Feb 14,  9:59am, S. Cowles wrote:
> }
> } In the following code, method 1 gives the expected results. Method
> } 2, however, breaks with the error: unknown file attribute. Is the
> } eval in Method 1 required, or is there a correct syntax to make the
> } dereference occur in Method 2 without an eval?
>
> The short answers are "not precisely" and "no".
>
> } 	# method 1:
> } 	b=3D$(echo "${key}=3D( ${(@)${(P)val}} )")
> } 	eval $b
>
> You don't need the $(echo) and the assignment to $b here.  It should be
> enough to do
>
> 	eval ${key}'=3D( ${(P)val} )'
>
> (note placement of single quotes).
>
> } 	# method 2:
> } 	${key}=3D( ${(@)${(P)${val}}} )
>
> This syntax is not an assignment, because the stuff to the left of the
> equals sign is not an identifier name.  (This used to work in older
> versions of zsh because the variable was expanded before zsh looked
> for assignment syntax, but that was incompatible with other shells.)
>
> Even if this were an assignment, The ${(@)...} is extraneous when the
> whole thing is not in double quotes.  And you don't need ${(P)${val}},
> just ${(P)val} is enough.