Emulates "Constants" by locking a given table to a metatable. Also adds functions to retrieve the table's keys, values, and entries.

const.lua

--[[
	clockworksquirrel.const
	Emulates "Constants" by locking a given table to a metatable.
	Also adds functions to retrieve the table's keys, values, and entries.
	
	Usage: <table> const(<table> table)
--]]

local t = require(script.Parent.t)

return function(Table)
	assert(t.table(Table))
	
	local Data = {
		Keys = {},
		Values = {},
		Entries = {}
	}
	
	for Key, Value in next, Table do
		Data.Keys[#Data.Keys + 1] = Key
		Data.Values[#Data.Values + 1] = Value
		Data.Entries[#Data.Entries + 1] = {Key, Value}
	end
	
	return setmetatable({}, {
		__index = function(self, key)
			if (key == '.keys') then return Data.Keys end
			if (key == '.values') then return Data.Values end
			if (key == '.entries') then return Data.Entries end
			
			return Table[key]
		end,
		
		__newindex = function() error('Cannot append to locked table', 2) end,
		__metatable = 'This table is locked'
	})
end