[Lua sample] Simple demo of a Lua code #demo

sample.lua

-- Use a builder to safely make objects
function build_complex(r, i)
  return {real = r, img = i}
end

-- Accessing a value with a key
complex = build_complex(3, 4)
assert(complex["real"] == complex.real)
print(complex.real)

-- Calling a "member function"
function _conjugate(c)
  c.img = -c.img
end
complex.conjugate = _conjugate
complex.conjugate(complex)
complex:conjugate()
print(complex.img)

-- Operator overloading via a metatable
mt = {}
mt.__add = function(c1, c2)
  return build_complex(c1.real + c2.real, c1.img + c2.img)
end

function build_complex(r, i)
  local ret = {real = r, img = i}
  setmetatable(ret, mt)
  return ret
end

complex = build_complex(complex.real, complex.img)
print((complex + complex).real)