Module:No globals: Difference between revisions

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don't bother saving old __index or __newindex
m 14 revisions imported: Trying again with Templates and Modules—Importing Mbox style Templates ({{Mbox}} and {{Ambox}})
 
(27 intermediate revisions by 21 users not shown)
Line 1: Line 1:
local mt = getmetatable(_G) or {}
local mt = getmetatable(_G) or {}
function mt.__index (t, k)
function mt.__index (t, k)
if k ~= 'name' and k ~= 'arg' then
if k ~= 'arg' then
error('Tried to read nil global ' .. tostring(k), 2)
error('Tried to read nil global ' .. tostring(k), 2)
end
end
Line 7: Line 7:
end
end
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

Latest revision as of 13:02, 17 October 2022

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 require('Module:No globals') 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)