diff --git a/module.lua b/module.lua
index 6dc86d2..dff5820 100644
--- a/module.lua
+++ b/module.lua
@@ -1,11 +1,11 @@
-local DECLARED, MUTABLE, PUBLIC = 1, 2, 4
-local DECLARED_KEY, MUTABLE_KEY, PUBLIC_KEY = 'declared', 'mutable', 'public'
-local MODIFIER_VALUE = {[DECLARED_KEY]=DECLARED, [MUTABLE_KEY]=MUTABLE, [PUBLIC_KEY]=PUBLIC}
-
 local band, bor, bnot = bit.band, bit.bor, bit.bnot
 local _G = getfenv(0)
 
-local _state, _data, _metadata  = {}, {}, setmetatable({}, {__index=function() return 0 end})
+local FIELD, ACCESSOR, MUTABLE, PUBLIC = 1, 2, 4, 8
+local ACCESSOR_KEY, MUTABLE_KEY, PUBLIC_KEY = 'accessor', 'mutable', 'public'
+local MODIFIER = {[ACCESSOR_KEY]=ACCESSOR, [MUTABLE_KEY]=MUTABLE, [PUBLIC_KEY]=PUBLIC}
+
+local _state, _data, _metadata  = {}, {}, {}
 
 --local function_mt = {
 --	__call = function(self, ...)
@@ -15,63 +15,74 @@ local _state, _data, _metadata  = {}, {}, setmetatable({}, {__index=function() r
 --		getfenv(f).__ = temp
 --	end,
 --}
---local method_mt = {
---	__call = function(self, ...)
---		local f = self[1]
---		local temp = getfenv(f)
---		setfenv(f, state[self])
---		f(...)
---		setfenv(f, temp)
---	end,
---}
+local metadata_mt = {__index=function() return 0 end}
 local environment_mt = {
 	__metatable = false,
 	__index = function(self, key)
-		if _metadata[self][key] == 0 then return _G[key] or error('No key "'..key..'".', 2) end
-		return _data[self][key]
+		local value, properties = _data[self][key], _metadata[self][key]
+		if band(FIELD, properties) ~= 0 then
+			return value
+		elseif band(ACCESSOR, properties) ~= 0 then
+			return value(key)
+		else
+			return _G[key] or error('No key "'..key..'".', 2)
+		end
 	end,
 	__newindex = function(self, key, value)
-		local m = _metadata[self][key]
-		if band(bor(DECLARED, MUTABLE), m) == DECLARED then error('"'..key..'" is immutable.', 2) end
+		local properties = _metadata[self][key]
+		if properties == 0 then
+			_metadata[self][key] = FIELD
+		elseif band(MUTABLE, properties) == 0 then
+			error('"'..key..'" is immutable.', 2)
+		end
 		_data[self][key] = value
-		_metadata[self][key] = bor(1, m)
 	end,
 }
 local interface_mt = {
 	__metatable = false,
 	__index = function(self, key)
-		if band(PUBLIC_V, _metadata[self][key]) == 0 then error('No key "'..key..'".', 2) end
-		return _data[self][key]
+		local value, properties = _data[self][key], _metadata[self][key]
+		if band(FIELD, properties) ~= 0 then
+			return value
+		elseif band(ACCESSOR, properties) ~= 0 then
+			return value(key)
+		else
+			error('No key "'..key..'".', 2)
+		end
 	end,
 	__newindex = function() error('Unsupported operation.', 2) end,
 }
 local modifier_mt = {
 	__metatable = false,
 	__call = function(self, key)
-		_state[self] = MODIFIER_VALUE[key]
+		_state[self] = bor(_state[self], MODIFIER[key])
+		return self
 	end,
 	__index = function(self, key)
-		local value = MODIFIER_VALUE[key]
+		local value = MODIFIER[key]
 		if not value then error('Unsupported operation.', 2) end
 		_state[self] = bor(_state[self], value)
 		return self
 	end,
 	__newindex = function(self, key, value)
-		if _metadata[self][key] then error('Duplicate key "'..key..'".', 2) end
+		if _metadata[self][key] ~= 0 then error('Duplicate key "'..key..'".', 2) end
 		_data[self][key] = value
-		_metadata[self][key] = bor(_state[self], DECLARED)
+		_metadata[self][key] = _state[self]
+		_state[self] = 0
 	end,
 }
 function aux_module()
 	local modifier, environment, interface = setmetatable({}, modifier_mt), setmetatable({}, environment_mt), setmetatable({}, interface_mt)
-	local data, metadata = {mutable=modifier, public=modifier}, {mutable=1, public=1}
+	local data = {[ACCESSOR_KEY]=modifier, [MUTABLE_KEY]=modifier, [PUBLIC_KEY]=modifier}
+	local metadata = setmetatable({[ACCESSOR_KEY]=ACCESSOR, [MUTABLE_KEY]=ACCESSOR, [PUBLIC_KEY]=ACCESSOR}, metadata_mt)
 
 	_data[modifier], _data[environment], _data[interface] = data, data, data
 	_metadata[modifier], _metadata[environment], _metadata[interface] = metadata, metadata, metadata
-	_state[modifier] = 1
+	_state[modifier] = 0
 
-	environment.mutable.__()
+	environment.mutable.__ = nil
 	environment.m = environment -- TODO for compatibility, remove later
+	environment.private = environment -- TODO for compatibility, remove later
 
 	setfenv(2, environment)
 	return interface