A way to write switch-case statements in lua.

switch.lua

print "Hello, switch"

-- If the default case does not have to be handled, we can use the following auxiliary function:
local function switch(value)
	-- Handing `cases` to the returned function allows the `switch()` function to be used with a syntax closer to c code (see the example below).
	-- This is because lua allows the parentheses around a table type argument to be omitted if it is the only argument.
	return function(cases)
		
		-- The default case is achieved through the metatable mechanism of lua tables (the `__index` operation).
		setmetatable(cases, cases)
		
		local f = cases[value]
		if f then
			f()
		end
	end
end

-- Suppose we want to write the equivalent lua code of the following c code:
-- switch (a) {
-- case 1:
--   printf("Case 1.\n");
--   break;
-- case 2:
--   printf("Case 2.\n");
--   break;
-- case 3:
--   printf("Case 3.\n");
--   break;
-- default:
--   printf("Case default.\n");
-- }
local x = 2
switch (x) {
	[1] = function()	-- for case 1
		print "Case 1."
	end,
	[2] = function()	-- for case 2
		print "Case 2."
	end,
	[3] = function()	-- for case 3
		print "Case 3."
	end,
	__index = function()	-- for case default, can be omitted if not needed
		print "Case default."
	end
}

Also, I just realized that I use a simple Lua idiom that basically works like switch-case (not exactly, but it's very similar). I'll leave it there, I hope someone may find it useful:

print "Hello, switch"
local x = 2
local result =
	   x == 1 and "Case 1."
	or x == 2 and "Case 2."
	or x == 3 and "Case 3."
	or "Case default."
print(result)

This removes the need of using metatable entirely.