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Re: namref dicussion continued: [PATCH] export -r reference


From: Chet Ramey
Subject: Re: namref dicussion continued: [PATCH] export -r reference
Date: Sun, 8 May 2016 19:28:18 -0400
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.0

On 5/4/16 12:30 PM, Piotr Grzybowski wrote:
> Hey,
> 
>  after another discussion with Grisha, and following one of his remarks, I 
> kindly request your opinion on the attached patch (like: bad, not needed, 
> already done, weak as it stands, harmful, etc.). It addresses the exporting 
> of identifiers with have nameref attribute set.
>  at the moment we have:
> 
> #a=10; declare -nx ra=a; bash -c 'echo "a:$a, ra:$ra, ra_excl:${!ra}."' 
> a:, ra:a, ra_excl:.
> #a=10; declare -n ra=a; export ra; bash -c 'echo "a:$a, ra:$ra, 
> ra_excl:${!ra}."'
> a:10, ra:a, ra_excl:10

I'm not going to add another option to export before bash-4.4 is released.
This discussion, as useful as it's been, has already delayed the release
too long.

The above behavior is a pretty straightforward application of the nameref
rules: in the first case, ra is assigned `a' but never dereferenced; in
the second case, `ra' is dereferenced when used as the argument to
`export'.  `unset' works the same way.  bash and ksh93 work the same with
the second case, though ksh93, for some reason, doesn't allow -nx in any
combination as options to typeset.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/



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