do -- Require luajit __pairs metamethod to be enabled
    local enabled
    local t = setmetatable({}, { __pairs = function() enabled = true; return function() end end })
    for _ in pairs(t) do
    end
    if not enabled then
        error("This thing requires luajit with __pairs metamethod enabled")
    end
end


local function make_proxy(actual, name)
    local function fmt(...) print(string.format(...)) end
    local function get_trace(label)
        return debug.traceback(label,3):gsub("([^\n]+)", "| %1")
    end

    local proxy = {} -- this must be empty to intercept every access
    local mt = {
        __index = function (_self, k)
            fmt("* %s.self.%s -- %s", name, k, get_trace('read'))
            return actual[k]   -- access the original table
        end,

        __newindex = function (_self, k, v)
            fmt("* %s.self.%s = %s -- %s", name, k, v, get_trace('write'))
            actual[k] = v   -- update original table
        end,
        __pairs = function (self)
            -- wrap `next` to enable proxy hits during traversal
            return function (tab, key)
                local index, value = next(actual, key)
                return index, value ~= nil and self[index]
            end, self, nil
        end,
    }
    return setmetatable(proxy, mt)
end

return make_proxy