-- Use a deep clone here, so that people can't modify the cached entity
return entityModule.create( mw.clone( entity ) )

-- This creates an read-only dummy table for accessing the real data.
--
-- @param data table Data to access
-- @param seen table|nil Table of already-seen tables.
-- @return table
local function dataWrapper( data, seen )
	local t, dummyValue, changes = {}, {}, nil
	seen = seen or { [data] = t }
	local function pairsfunc( s, k )
		k = next( changes or data, k )
		if k ~= nil then
			return k, t[k]
		end
		return nil
	end
	local function ipairsfunc( s, i )
		i = i + 1
		if t[i] ~= nil then
			return i, t[i]
		end
		-- no nil to match default ipairs()
	end
	local mt = {
		__index = function ( tt, k )
			assert( t == tt )
			if changes and changes[k] ~= dummyValue then
				return changes[k]
			end
			local v = data[k]
			if type( v ) == 'table' then
				seen[v] = seen[v] or dataWrapper( v, seen )
				return seen[v]
			end
			return v
		end,
		__newindex = function ( tt, k, v )
			assert( t == tt )
			if not changes then
				changes = {}
				for k in pairs( data ) do
					changes[k] = dummyValue
				end
			end
			changes[k] = v
		end,
		__pairs = function ( tt )
			assert( t == tt )
			return pairsfunc, t, nil
		end,
		__ipairs = function ( tt )
			assert( t == tt )
			return ipairsfunc, t, 0
		end,
	}

	-- This is just to make setmetatable() fail
	mt.__metatable = mt

	return setmetatable( t, mt )
end

local cached = { P31 = 'Q5' }

local function getEntity()
	return dataWrapper( cached )
end

-- This demonstrates that cross-invoke communication is impossible
local e1 = getEntity()
local e2 = getEntity()
e1.P31 = 'muhaha'
local e3 = getEntity()
print( e1.P31, e2.P31, e3.P31 ) --> muhaha  Q5  Q5