local model=class('model')
local globaldb=class('globaldb')

-- The global environment contents for a model.  A list of the builtin
-- functions and classes that get installed in the global environment of
-- a world model.
--
-- This barely counts as 'sandboxing' - it's more just a mechanism to
-- keep the user from unintentionally thinking that some functionality is
-- available when it's not.  For true sandboxing, you need to not import
-- functions into the lua interpreter at all.
--
-- Omitted from this list: debug, dofile, getfenv, io, jit,
-- load, loadfile, loadstring, module, newproxy, os, package,
-- pcall, require, xpcall
--

model.global_contents = { "assert", "bit", "error", "getmetatable", "inspect",
    "ipairs", "math", "next", "pairs", "print", "rawequal", "rawget", "rawset",
    "select", "setmetatable", "tonumber", "tostring", "type", "unpack" }

-- make a world model.
--
function model.make()
    genv = {}
    genv._G = genv
    meta = {}
    meta.class_db = classdb.create()
    meta.global_db = globaldb.create()
    meta.source_db = {}
    meta.tangible_db = {}
    meta.__newindex = function() error("world model global environment is read-only") end
    -- meta.__metatable = false
    genv.class = classdb.accessor(meta.class_db)
    genv.global = make_global_accessor(meta.global_db)
    for i,name in ipairs(world.global_contents) do
        genv[name] = _G[name]
    end
    setmetatable(genv, meta)
    return genv
end