Re: do I win the "most pointless use of ZSH" award? ;)

[Peter Stephenson <pws@xxxxxxx>]

> >         zsh% i=/foo; for ((i=0; i<10; i++)) echo $i
> >         zsh: bad math expression: operand expected at `/foo'
> > 
> > Is this a bug or a feature that I'm entirely missing?
> 
> It's a feature.  The value of any parameter that appears in math context
> is evaluated as an expression (up to a maximum recursion depth, I forget
> what just now).  So
> 
> 	i=foo/bar
> 	((i))
> 
> is the same as
> 
> 	((foo/bar))
> 
> and so on for the values of `foo' and `bar'.

But that's not what's happening here, it's assigning to i.  Try

  i=/irrelevant
  (( i = 0 ))

It never needs to know the original value of i.  The problem is that the
value, which is never used, is retrieved at the point where the identifier
is identified.  This is quite a serious bug because it means scalars can't
reliably be used in arithmetic expressions at all.

The fix is probably to mark the thing on the math stack as a parameter and
retrieve it when we need the value.  That doesn't look like a quick change.

-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR Ltd., Unit 300, Science Park, Milton Road,
Cambridge, CB4 0XL, UK                          Tel: +44 (0)1223 392070


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