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Date: Sat, 14 May 2011 11:03:36 +0200
Message-ID: <BANLkTi=bMHd4RRAj5TannqbVkqjz=y3iUQ@mail.gmail.com>
Subject: Re: Infinite recursions in math evaluation
From: Mikael Magnusson <mikachu@gmail.com>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: zsh workers <zsh-workers@zsh.org>
Content-Type: text/plain; charset=UTF-8

On 14 May 2011 06:36, Bart Schaefer <schaefer@brasslantern.com> wrote:
> On May 13, 11:37pm, Mikael Magnusson wrote:
> }
> } [...]  Aha, actually a=a; $(( a )) crashes in the same way. (On
> } a machine with a presumably less optimized/buggy compile, it does
> } print "zsh: math recursion limit exceeded" instead of crashing). Is it
> } simply a user error? I wouldn't expect either of these expressions to
> } recursively look up values of the parameter until it encountered a
> } number, but this is indeed what happens:
> } % a=b; b=c; c=d; d=e; e=f; f=5; echo $(( a ))
> } 5
> } bash does the same...
> }
> } I scanned quickly through the "Arithmetic Evaluation" section and
> } found nothing suggesting that this should happen.
>
> It's implicit in this:
>
>    Named parameters and subscripted arrays can be referenced by name
>    within an arithmetic expression without using the parameter expansion
>    syntax.  For example,
>
>        ((val2 = val1 * 2))
>
>    assigns twice the value of $val1 to the parameter named val2.

Well, I read that part, but

> "The value of $val1" in an arithmetic context is the result of doing
> arithmetic evaluation on whatever is stored in the parameter.  If
> that's the name of another (or even the same) parameter, then ...

How did you get this from the quoted part?

-- 
Mikael Magnusson