3 ms·

Yep, it's just late binding. If you want that in the JVM, you can use Groovy, which does just that.

• brabel 5y ago
  Example: class Fire{} class Water {} class Grass {} class Ice {} def eff(Fire f, Grass g) { 'burn' } def eff(Fire f, Ice ice) { 'melt' } def eff(Water w, Grass g) { 'grow' } def eff(Water w, Ice ice) { 'freeze' } def eff(a, b) { 'undefined' } println eff(new Fire(), new Grass()) println eff(new Fire(), new Ice()) println eff(new Water(), new Grass()) println eff(new Water(), new Ice()) println eff(new Ice(), new Water()) Prints: burn melt grow freeze undefined
  • pjmlp 5y ago
    That is method overloading, which isn't the same as multi-dispatch.
    • brabel 5y ago
      What would multi-dispatch do differently???
      • adgjlsfhk1 5y ago
        the difference is that overloading works on compile time types but dispatch works on runtime types. This matters because when you write a generic algorithm, you don't know the type, so don't get the right behavior with overloading (you get the generic fallback).
        • brabel 5y ago
          In Groovy, dynamic dispatch is used. It's the runtime types that matter, as my example makes patently clear. EDIT: to make it even more obvious there's no difference: class Fire{} class Water {} class Grass {} class Ice {} def eff(Fire f, Grass g) { 'burn' } def eff(Fire f, Ice ice) { 'melt' } def eff(Water w, Grass g) { 'grow' } def eff(Water w, Ice ice) { 'freeze' } def eff(a, b) { 'undefined' } // hide compile-time types Object fire = new Fire() Object grass = new Grass() Object ice = new Ice() Object water = new Water() println eff(fire, grass) println eff(fire, ice) println eff(water, grass) println eff(water, ice) println eff(ice, water) Prints: burn melt grow freeze undefined
    • ThomasMoll 5y ago
      Groovy supports multi-dispatch, if you needed to encapsulate a generic type, the compile would dynamically resolve that type correctly. See my example in Java (which has method overloading, but not MD)