Working

luprex/syslua/model.lua

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+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