ES6, niente this, niente weakmap

ProprietàPrivate.js

const Point = (x = 0, y = 0) => ({
    setCartesianCoordinates(_x, _y) {
        x = _x; y = _y;
    },
    setPolarCoordinates(radius, angle) {
        x = radius * Math.cos(angle);
        y = radius * Math.sin(angle);
    },
    getCartesianCoordinates() {
        return { x, y }
    },
    getPolarCoordinates() {
        const radius = Math.sqrt(x**2 + y**2)
        const angle = 
              x === 0 ? y > 0 ? Math.PI/2 : -Math.PI/2 : Math.atan(y/x) + ((y < 0) ? Math.PI : 0)
        return { radius, angle }
    },
});

const point = Point(10, 10);
console.log("a point: ", point)
console.log(point.getCartesianCoordinates())
console.log(point.getPolarCoordinates())
point.setCartesianCoordinates(-10, 7)
console.log(point.getPolarCoordinates())
point.setPolarCoordinates(10, Math.PI/7)
console.log(point.getCartesianCoordinates())
console.log("----------------------------------------------------------")
console.log("----------------------------------------------------------")
console.log("----------------------------------------------------------")


const ImmutablePoint = (x = 0, y = 0) => ({
    setCartesianCoordinates(_x, _y) {
        return ImmutablePoint(_x, _y)
    },
    setPolarCoordinates(radius, angle) {
        const _x = radius * Math.cos(angle);
        const _y = radius * Math.sin(angle);
        return ImmutablePoint(_x, _y)
    },
    getCartesianCoordinates() {
        return { x, y }
    },
    getPolarCoordinates() {
        const radius = Math.sqrt(x**2 + y**2)
        const angle = 
              x === 0 ? y > 0 ? Math.PI/2 : -Math.PI/2 : Math.atan(y/x) + ((y < 0) ? Math.PI : 0)
        return { radius, angle }
    },
});


const immutablePoint = ImmutablePoint(10, 10);
console.log(immutablePoint)
console.log(immutablePoint.getCartesianCoordinates())
console.log(immutablePoint.getPolarCoordinates())
console.log("it creates a new point: ", immutablePoint.setCartesianCoordinates(-10, 7).getPolarCoordinates())
console.log("the previous was not affected: ", immutablePoint.getPolarCoordinates())
console.log("----------------------------------------------------------")
console.log("----------------------------------------------------------")
console.log("----------------------------------------------------------")

const COORDINATES = Object.freeze({
  CARTESIAN: "CARTESIAN",
  POLAR: "POLAR"
})

const ImmutableSuperPoint = (xr = 0, ya = 0, mode = COORDINATES.CARTESIAN) => {
  
  let x, y
  if(mode === COORDINATES.POLAR) {
      x = xr * Math.cos(ya);
      y = xr * Math.sin(ya);
  } else if(mode === COORDINATES.CARTESIAN) {
      x = xr;
      y = ya;
  } else {
      throw new Error(`${mode} is not a valid coordinate system`)
  }
  
  return {
    setCartesianCoordinates(_x, _y) {
        return ImmutableSuperPoint(_x, _y)
    },
    setPolarCoordinates(radius, angle) {
        const _x = radius * Math.cos(angle);
        const _y = radius * Math.sin(angle);
        return ImmutableSuperPoint(_x, _y)
    },
    getCartesianCoordinates() {
        return { x, y }
    },
    getPolarCoordinates() {
        const radius = Math.sqrt(x**2 + y**2)
        const angle = 
              x === 0 ? y > 0 ? Math.PI/2 : -Math.PI/2 : Math.atan(y/x) + ((y < 0) ? Math.PI : 0)
        return { radius, angle }
    },
}};

const isp1 = ImmutableSuperPoint(50, 50, COORDINATES.CARTESIAN)
const isp2 = ImmutableSuperPoint(20, Math.PI/4, COORDINATES.POLAR)
console.log(isp1.getPolarCoordinates())
console.log(isp2.getCartesianCoordinates())


// WARNING
// Ogni entità creata possederà, per forza di cose, una copia dei 4 metodi
// Se creo un miliardo di punti, ciaone memoria!