Re: Deep __newindex on assignment?

[Peter Cawley <lua@...>]

On Tue, Dec 22, 2009 at 6:40 PM, Todd Berkebile
<todd_berkebile@hotmail.com> wrote:
>  local pos = propBag.Position  -- pos is now the proxy object wrapping the Point userdata
>  pos.z = 10                    -- this will use the proxy's __newindex thus setting the value in propBag
>  otherBag.Position = pos
>  assert(propBag.Position ~= otherBag.Position) -- this would fail as both were modified
>
> With the above syntax I wouldn't want the original propBag to be modified.

Why not? To me (and effectively to the Lua compiler), the following
two bits of code are equivalent:
---------
local temp = propBag.Position
temp.z = 10
---------
propBag.Position.z = 10
---------
Hence in both cases, I would want the original propBag to be modified.