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This module implements {{user}}. For documentation, please see the template page.

Technical details

While the {{user}} template is only a wrapper for Module:UserLinks, by implementing it as a Lua module we make significant gains in performance. It is roughly twice as fast as accessing Module:UserLinks from wikitext. For example, this module rendered a test page containing nothing but 1000 {{user}} transclusions in 3.9 seconds, whereas the version that called Module:UserLinks from wikitext rendered it in 7.7 seconds.

The performance gains are achieved by reducing the number of parameters that are looked up from wikitext. In particular, the link codes, "t" and "c", along with the "span=no" option, are passed directly to UserLinks. Also, UserLinks looks up the arguments "user", "User", "project", "Project", "lang", and "Lang". From wikitext, each parameter is checked twice – once for the #invoke text and once for the calling template – and each check is relatively resource-heavy. From Lua, each parameter is only checked once, and the individual checks take much less time. This means that on average, maybe nine argument lookups are saved in each invocation by using this module. On pages with hundreds or thousands of invocations, this adds up to a lot of argument lookups saved.



--[=[
-- This module implements {{user}}. {{user}} is a high-use template, sometimes
-- with thousands of transclusions on a page. This module optimises the
-- template's performance by reducing the number of parameters called from
-- wikitext, while still allowing all the features provided by
-- [[Module:UserLinks]]. It is about twice as fast as the version of {{user}}
-- that called the {{user-multi}} template from wikitext.
--]=]

local mUserLinks = require('Module:UserLinks')
local mShared = require('Module:UserLinks/shared')
local yesno = require('Module:Yesno')

local p = {}

local function validateArg(arg)
	-- Validates one argument. Whitespace is stripped, and blank arguments
	-- are treated as nil.
	if not arg then
		return nil
	end
	arg = arg:match('^%s*(.-)%s*$')
	if arg ~= '' then
		return arg
	else
		return nil
	end
end

function p.main(frame)
	-- Grab the user, project and lang args from wikitext.
	local argKeys = {
		user = {
			1,
			'User',
			'user'
		},
		project = {
			2,
			'Project',
			'project'
		},
		lang = {
			3,
			'Lang',
			'lang'
		}
	}
	local origArgs = frame:getParent().args
	local args = {}
	for argKey, t in pairs(argKeys) do
		for i, origArgKey in ipairs(t) do
			local value = origArgs[origArgKey]
			value = validateArg(value)
			if value then
				args[argKey] = value
				-- If we have found a value, break the loop. For the average
				-- invocation this saves two argument lookups.
				break
			end
		end
	end
	
	-- Generate options. Some of these need wikitext args also.
	local options = {
		span = false,
		separator = validateArg(origArgs.separator) or 'dot',
		isDemo = yesno(validateArg(origArgs.demo))
	}
	
	-- Input the codes directly. This saves two argument lookups for each
	-- invocation.
	local codes = {'t', 'c'}
	
	-- Plug the data into [[Module:UserLinks]].
	local snippets = mUserLinks.getSnippets(args)
	local links = mUserLinks.getLinks(snippets)
	local success, result = pcall(mUserLinks.export, codes, links, options)
	if success then
		return result
	else
		return mShared.makeWikitextError(result, options.isDemo)
	end
end

return p