Promise- and callback-heavy code relies on passing objects around a lot, and having to enclose objects in callbacks is annoying. What if we could *almost* do `object:method` to reference a version of the method that includes the object?

idea_methods_with_self.lua

local withMeta = {}
function withMeta:__index(key)
	local object = self._with
	return function(...)
		return object[key](object, ...)
	end
end

local function with(object)
	return setmetatable({ _with = object }, withMeta)
end

local function makeTupleConcat(...)
	local baseTupleLength = select("#", ...)
	local baseTuple = {...}

	return function(...)
		local newTupleLength = select("#", ...)
		local newTuple = {...}

		local fullTupleLength = baseTupleLength + newTupleLength
		local fullTuple = table.create(baseTupleLength + newTupleLength)

		table.move(baseTuple, 1, baseTupleLength, 1, fullTuple)
		table.move(newTuple, 1, newTupleLength, baseTupleLength + 1, fullTuple)

		return unpack(fullTuple, 1, fullTupleLength)
	end
end

local asIfMeta = {}
function asIfMeta:__index(key)
	local object = self._with
	return function(potentiallySelf, ...)
		local concatArgsTuple
		if potentiallySelf == self then
			concatArgsTuple = makeTupleConcat(object, ...)
		else
			concatArgsTuple = makeTupleConcat(potentiallySelf, ...)
		end

		return function(...)
			return object[key](concatArgsTuple(...))
		end
	end
end

function asIfMeta:__call(...)
	local func = self._with
	local concatArgsTuple = makeTupleConcat(...)
	return function(...)
		return func(concatArgsTuple(...))
	end
end

local function asIf(object)
	return setmetatable({ _with = object }, asIfMeta)
end

-- Examples:

local model = Instance.new("Model")

local destroy = with(model).Destroy
destroy()

local destroy2 = asIf(model):Destroy()
destroy2()

-- Providing the first parameters to object methods:

local someObject = {}

function someObject:log(logType, ...)
	if logType == "info" then
		print(...)
	elseif logType == "warn" then
		warn(...)
	else
		error(string.format("Bad logType %s", tostring(logType)))
	end
end

local logInfo = asIf(someObject):log("info")
local logWarn = asIf(someObject):log("warn")

logInfo("This is an info message!")
logWarn("This is a warning", "with multiple args!")

-- Providing the first parameters to any function:

local contextualPrint = asIf(print)("[" .. script.Name .. "]")

contextualPrint("This is printing with context!")

-- Using with a promise:

Promise.delay(0.5):andThen(asIf(particleEmitter):Emit(1))