Module:No globals: Difference between revisions

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meta>Jackmcbarn
Created page with 'local mt = getmetatable(_G) or {} local oldIndex = mt.__index or function() return nil end mt.__index = function(t, k) if k ~= 'name' and k ~= 'arg' then erro...'
 
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Line 1: Line 1:
local mt = getmetatable(_G) or {}
local mt = getmetatable(_G) or {}
local oldIndex = mt.__index or function() return nil end
function mt.__index (t, k)
mt.__index = function(t, k)
if k ~= 'arg' then
if k ~= 'name' and k ~= 'arg' then
error('Tried to read nil global ' .. tostring(k), 2)
error('Tried to read nil global ' .. tostring(k), 2)
end
end
return oldIndex(t, k)
return nil
end
end
local oldNewindex = mt.__newindex or rawset
function mt.__newindex(t, k, v)
function mt.__newindex(t, k, v)
if k ~= 'name' and k ~= 'arg' then
if k ~= 'arg' then
error('Tried to write global ' .. tostring(k), 2)
error('Tried to write global ' .. tostring(k), 2)
end
end
oldNewindex(t, k, v)
rawset(t, k, v)
end
end
setmetatable(_G, mt)
setmetatable(_G, mt)

Latest revision as of 00:52, 3 September 2020

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.)

See also


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)