Re: array index and modulo

[Diego Nehab <diego@...>]

Hi,

I once wrote a little metatable trick to make an array
circular. Here is what I used

    -- circular array metatable
    local function wrap(t, k)
        return ((k-1)%(#t))+1
    end
    local lmt = {
        __index = function(t, k)
            if type(k) == "number" then
                return rawget(t, wrap(t, k))
            else
                return nil
            end
        end
    }

    -- turns a table into a circular array
    function circular(t)
        return setmetatable(t, lmt)
    end

Now you can do something like this

    a = circular{1, 2, 3, 4}
    for i = 1, 10 do
        print(a[i])
    end

    1
    2
    3
    4
    1
    2
    3
    4
    1
    2

[]s,
Diego.