루아-클로저

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루아에서 함수는 일급객체이다. 즉 숫자형과 문자열처럼 함수를 변수에 저장할 수 있다.

a = {log = print}
a.log("Hello World")

foo = function(x)
  return 2 * x
end

network = {
  {name = "grauna", IP = "210.26.30.34},
  {name = "arraial", IP = "210.26.30.23"}, 
  {name = "lua", IP = "210.26.23.12"}, 
  {name = "derain", IP = "210.26.23.20"},
}
table.sort(network, function (a, b) return (a.name > b.name) end)

function derivative (f, delta)
  delta = delta or 1e-4
  return function (x)
    return (f(x + delta) -f(x) / delta)
  end
end
 
c = derivative(math.sin)
print(math.cos(5.2), c(5.2))
--> 0.46851, 0.46851

Lib = {
  goo = function (x, y) return x * y end
}
Lib.foo = function (x, y) return x + y end
function Lib.bar (x, y) return x - y end

-- local function goo () print("goo") end
-- local goo; goo = function() print("goo") end
 
local foo
 
local function bar()
  return foo
end
 
function foo()
 print("local foo")
end

names = {"Peter", "Paul", "Mary"} 
grades = {Mary = 10, Paul = 7, Peter = 8}
function sortByGrade (names, grades)
  table.sort(names, function (i, j)
	return grades[i] > grades[j]
  end)
end

function newCounter()
  local count = 0
  return function()
	count = count + 1
	return count
  end
end
 
c1 = newCounter()
print(c1()) --> 1
print(c1()) --> 2