Module:utilities/require when needed

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A helper function which can be used in place of require if it's not certain that the module in question will be needed. If the module has already been loaded, then it is simply returned; if it hasn't, then it won't be loaded until it is first used.

This is generally useful when defining variables at the start of a module.

---

local loaded = package.loaded
local require = require
local setmetatable = setmetatable

return function(text, key)
	local module = loaded[text]
	
	if module then
		return key and module[key] or module
	end
	
	local mt = {}
	
	function mt:__index(k)
		module = module or key and require(text)[key] or require(text)
		return module[k]
	end
	
	function mt:__call(...)
		module = module or key and require(text)[key] or require(text)
		return module(...)
	end
	
	return setmetatable({}, mt)
end