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Re: [BUG] 'unset' fails silently under specific conditions


From: Chet Ramey
Subject: Re: [BUG] 'unset' fails silently under specific conditions
Date: Tue, 1 May 2018 21:20:42 -0400
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.7.0

On 5/1/18 6:27 PM, Martijn Dekker wrote:
> Op 01-05-18 om 19:36 schreef Chet Ramey:
>> OK, so which is it? Does an assignment statement preceding a special
>> builtin in a shell function create a local variable (as we discussed
>> just yesterday)
> 
> Huh? That was about 'typeset'/'declare'. How is that relevant here?

Do you really not remember? Let's roll tape.

You complained that `typeset +x' didn't `unexport' a variable. The reason
is that the variable assignment preceding the special builtin caused a
variable to be created at the global scope, and the `typeset' resulted in
a local variable being created. The upshot of that discussion was that in
order to implement the semantics you said you wanted at the time,

> 
>>  or does it create a global variable because `Posix'?
> 
> Yes. POSIX does not specify local variables at all, and even in a bash
> context I see nothing there to indicate that it should be local.

Maybe in Posix mode. It's true that Posix doesn't specify local
variables, and I made that same point yesterday, but I can see where
an assignment statement preceding a special builtin can create a
variable at the same context.

> The possibility that 'foo=bar :' might create a variable 'foo' that
> survives the ':' command, is exported, *and* is local to the function,
> hadn't occurred to me at all. POSIX is pretty strange sometimes but not
> *this* strange.

It would have had to to satisfy the semantics of your report from a
couple of days ago, and, as I said in my message yesterday, I ultimately
implemented those semantics.

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



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