Re: Multiple return value in __index metamethod

[Rici Lake <lua@...>]

On 10-Jul-07, at 7:58 PM, David Manura wrote:

> Jerome Vuarand <jerome.vuarand <at> ubisoft.com> writes:
> > Another solution that no one else proposed is to pass several keys to
> > your __index metamethods. You can do that by creating a table
>
> The following variant of that approach avoids constructing a table and 
> is
> reasonably straightforward and efficient:
>
>   value, delta = t[i], t[-i]
>
> (assuming the key i is a positive integer so that the domains of i
> and -i are mutually exclusive).
>
> I also like the common solution:
>
>   value, delta = t:pair(i)    -- just get used to it ;)

Yet another possibility is returning a tuple, implemented
as a function.

function pair(a, b) return a, b end

t = {pair(3, 0.25), pair(4, 1.0), pair(-3, 0.8)}

for _, p in ipairs(t) do
  local value, delta = p()
  ...
end