4. Модулі

----------------------------------------------------
-- 4. Модулі.
----------------------------------------------------


--[[  
-- Припустимо, що файл mod.lua виглядає так:
local M = {}

local function sayMyName()
  print('Hrunkner')
end

function M.sayHello()
  print('Why hello there')
  sayMyName()
end

return M

-- Інший файл може використовувати функцію mod.lua:
local mod = require('mod')  -- запускає файл mod.lua.

-- require це стандартний спосіб включення модулів.



-- require acts like:     (if not cached; see below)
local mod = (function ()
  <contents of mod.lua>
end)()
-- It's like mod.lua is a function body, so that
-- locals inside mod.lua are invisible outside it.

-- This works because mod here = M in mod.lua:
mod.sayHello()  -- Says hello to Hrunkner.

-- This is wrong; sayMyName only exists in mod.lua:
mod.sayMyName()  -- error

-- require's return values are cached so a file is
-- run at most once, even when require'd many times.

-- Suppose mod2.lua contains "print('Hi!')".
local a = require('mod2')  -- Prints Hi!
local b = require('mod2')  -- Doesn't print; a=b.

-- dofile is like require without caching:
dofile('mod2.lua')  --> Hi!
dofile('mod2.lua')  --> Hi! (runs it again)

-- loadfile loads a lua file but doesn't run it yet.
f = loadfile('mod2.lua')  -- Call f() to run it.

-- loadstring is loadfile for strings.
g = loadstring('print(343)')  -- Returns a function.
g()  -- Prints out 343; nothing printed before now.

--]]