Re: Possible zsh bug with unique tied vars in 4.0.4?

[Peter Stephenson <pws@csr.com>]

Steve Simmons wrote:
> The following sequence of commands shows unexpected performance in
> zsh when using tied variables and unique processing.  In brief, if
> you have tied variables FOO and foo and typeset one of them to unique
> (-U), you can use the other to assign non-unique values to the first.
> This is counter-intuitive at best :-), and I can see no use for this
> feature.  The manual page leads one strongly to believe that a single
> variable is created which simply has two names and two presentations;
> the experiment below shows that clearly there are other differences
> as well.

I think `strongly' is an overstatement since the manual page says the
two parameters `may otherwise be manipulated as normal' and indicates
that only the scalar can be exported.  However, it's certainly not
particularly useful that -U works that way.  It's more useful with some
of the other flags where you might want different padding (-L, -R, -Z)
or you might want to hide the value (-H) for just one of the parameters,
or mark just one of them as readonly (-r), even though these are
probably less used features.  The only really good reason for not
changing this is that it makes a mess of the internals to grope around
for the alternative parameter just in the case where they are tied and
just for certain flags.  I expect the documentation could be made more
explicit, though.

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


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