3 ms·

What language would that work in? C# only does compile time dispatch of overloaded methods and Common LISP doesn't have overloaded methods at all. I honestly c

• ajuc 11y ago
  > I honestly can't think of a language that even support overloading of methods based on run time types. Clojure does with multimethods ( http://clojure.org/runtime_polymorphism http://clojure.org/runtime_polymorphism ). I suspect lisp with meta object protocol does too, but I only heard about it, so can't confirm. EDIT: deleted my solution that worked without method overloading at all, cause I missed some constraints.
  • ajuc 11y ago
    Just an example: (derive ::wizard ::person) (derive ::warior ::person) (derive ::weapon ::thing) (derive ::dagger ::weapon) (derive ::sword ::weapon) (derive ::staff ::weapon) ;; defines dispatch function that returns (inheritable) categories to dispath ;; it's very simple in this case (defmulti wield! (fn [p1 p2 thing] [(type p2) (type thing)])) (defmethod wield! [::person ::thing] [p1 p2 thing] (say! p1 p2 " refuse")) (defmethod wield! [::person ::dagger] [p1 p2 thing] (take! p2 p1 thing) (say! p1 p2 "accepts.")) (defmethod wield! [::wizard ::staff] [p1 p2 thing] (take! p2 p1 thing) (say! p1 p2 " gladly accepts.")) (defmethod wield! [::warrior ::sword] [p1 p2 thing] (take! p2 p1 thing) (say! p1 p2 " gladly accepts.")) It obviously could be done in half the lines without using multimethods, but the result would be much less extensible. BTW, with just 2 lines you can add gandalf and it just works (because there are no conflicting methods right now). (derive ::gandalf ::wizard) (derive ::gandalf ::warrior) If there were any - you can set preferences to avoid errors.
• junke 11y ago
  Strictly speaking, yes, there are no method overloading in Common Lisp. On the other hand, you have optional arguments and generic functions. Now, what happens when a vampire or a werewolf bites a warrior? Here is a rough sketch: http://pastebin.com/raw.php?i=Uu7fAx6p http://pastebin.com/raw.php?i=Uu7fAx6p
  • junke 11y ago
    Of course, metamorphosis should happen only once: (unless (typep target 'werewolf) (with-scheduling ...))
• gpderetta 11y ago
  Surprisingly, C# does natively support multimethods, thanks to 'dynamic'.
• BruceM 11y ago
  Dylan (http://opendylan.org/ http://opendylan.org/) does that via generic functions / multiple dispatch. The object system in Dylan is derived from CLOS from Common Lisp. Dylan allows sealing of generic functions to limit extensibility where needed and can use that information (along with other information) to optimize, generate warnings, etc. define class <weapon> (<object>) end; define class <sword> (<weapon>) end; define class <wand> (<weapon>) end; define class <person> (<object>) end; define class <wizard> (<person>) end; define class <warrior> (<person>) end; define method wield (who :: <wizard>, what :: <wand>) => () ... end; define method wield (who :: <warrior>, what :: <sword>) => () ... end;