Module:If empty

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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.

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This module depends on the following other modules:

Module:Arguments

This module supports Template:If empty.

Tracking/maintenance category

Category:Instances of Template:If empty missing arguments (0)

local p = {}

function p.main(frame)
	local args = require('Module:Arguments').getArgs(frame, {wrappers = 'Template:If empty', removeBlanks = false})

	-- For backwards compatibility reasons, the first 8 parameters can be unset instead of being blank,
	-- even though there's really no legitimate use case for this. At some point, this will be removed.
	local lowestNil = math.huge
	for i = 8,1,-1 do
		if args[i] == nil then
			args[i] = ''
			lowestNil = i
		end
	end

	for k,v in ipairs(args) do
		if v ~= '' then
			if lowestNil < k then
				-- If any uses of this template depend on the behavior above, add them to a tracking category.
				-- This is a rather fragile, convoluted, hacky way to do it, but it ensures that this module's output won't be modified
				-- by it.
				frame:extensionTag('ref', '[[Category:Instances of Template:If_empty missing arguments]]', {group = 'TrackingCategory'})
				frame:extensionTag('references', '', {group = 'TrackingCategory'})
			end
			return v
		end
	end
end

return p