Módulo:No globals

This Lua module is used on many pages and changes may be widely noticed. Test changes in the module's /sandbox or /testcases subpages. Consider discussing changes on the talk page before implementing them.

Tranclusion count updated automatically (see documentation).

This módulo is used in system messages.
Changes to it can cause immediate changes to the Wikipedia user interface. To avoid large-scale disruption, any changes should first be tested in this módulo's /sandbox or /testcases subpage, or in your own user space. The tested changes can then be added in one single edit to this módulo. Please discuss any changes on the talk page before implementing them.

This module is subject to page protection. It is a highly visible module in use by a very large number of pages, or is substituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it is protected from editing.

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)

See also