Re: __index function in a metatable shared by several tables

[David Given <dg@...>]

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Tim Hunter wrote:
[...]
> Is there any way for the function f to modify o.test? In my code there
> could be multiple o tables, all sharing the t metatable. I would like
> function f to store state information in each individual o table.

The way your code is set up, no, there isn't --- that's because you actually
have two metatables, one of which is hooked up to the other. o's metatable is
a table with a metatable whose __index is doing the work. By the time you get
to the second metatable, the context is lost.

Was this intentional? Because if it wasn't, you can just use a single
metatable, and the context is passed in as the first parameter to __index:

m = {__index =
  function(x, k)
    local function f()
      print("You called " .. k)
      x.test = x.test + 1
    end
    return f
  end
}

t = setmetatable({test = 1}, m)

print(t.test)
t.foo()
print(t.test)


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