Module: No globals
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This module causes an error if any nil global is read or if any global is written to, with the exception of arg. To use, add <syntaxhighlight lang="lua" inline>require('Module:No globals')</syntaxhighlight> to the top of the module using it. The arg variable is excluded because it is necessary for Scribunto's require function to work properly. (See the Scribunto source code here.)
local mt = getmetatable(_G) or {} function mt.__index (t, k) if k ~= 'arg' then error('Tried to read nil global ' .. tostring(k), 2) end return nil end function mt.__newindex(t, k, v) if k ~= 'arg' then error('Tried to write global ' .. tostring(k), 2) end rawset(t, k, v) end setmetatable(_G, mt)