LockGlobalsStandAlone.ttslua

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--- Partially lock the _G global variable table.
-- Include this AFTER creating any necessary globals to prevent new ones.
--
-- - Existing globals can still be read AND WRITTEN.
-- - Cannot read non-existent globals.
-- - Cannot write new globals.
--
-- This helps catch typos where what was meant to access a local instead
-- references a (hopefully non-existent) global, as well as forgetting to use
-- "local" when creating objects.
--
-- @author Darrell
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-- Index is only called when the key does not already exist.
local _lockGlobalsMetaTable = {}
function _lockGlobalsMetaTable.__index(table, key)
    error('Accessing missing global "' .. tostring(key or '<nil>') .. '", typo?', 2)
end
function _lockGlobalsMetaTable.__newindex(table, key, value)
    error('Globals are locked, cannot create global variable "' .. tostring(key or '<nil>') .. '"', 2)
end
setmetatable(_G, _lockGlobalsMetaTable)