Module:Existsmod

Documentation for this module may be created at Module:Existsmod/doc

-- <nowiki>
--------------------------------------------------------------------------------
-- An inexpensive alternative to {{#ifexist}} which looks for a given module,
-- and returns one of two values depending on whether it was found.
--
-- Syntax:
-- {{#invoke:Existsmod|main|<module-name>|<value-if-found>|<value-if-missing>}}
--------------------------------------------------------------------------------
local p = {}

local checkType = require("libraryUtil").checkType
local normalize = require("Dev:NormalizeModuleName")
local getArgs = require("Dev:Arguments").getArgs

function p.module_exists(name, foundVal, missingVal)
	checkType("Dev:Existsmod", 1, name, "string", true)

	if name then
		name = table.concat{normalize(name)}

		if package.loaded[name] then
			return foundVal
		else
			local _, val = pcall(package.loaders[2], name)

			if type(val) == "function" or type(val) == "string" then
				return foundVal 
			end
		end
	end

	return missingVal
end

function p.main(frame)
	local args = getArgs(frame)

	return p.module_exists(args[1], args[2], args[3])
end

return p

-- </nowiki>
-- (Add categories here.)