dispatch

Meikel Brandmeyer wrote a post on dispatch in Clojure with the URL title Static vs Dynamic. He writes: Protocols are not the only place where we have a trade-off of static vs. dynamic. There are several places where such a trade-off can be spotted. He provides the following example of static dispatch in a protocol: (defprotocol Flipable (flip [thing])) (defrecord Left [x]) (defrecord Right [x]) (extend-protocol Flipable Left (flip [this] (Right. (:x this))) Right (flip [this] (Left. (:x this)))) Now it is true that each record maps to a 'class' on the JVM that is compiled. If you try and

I'm using SpriteKit's collision detection. It has a callback that looks like this: - (void)didBeginContact:(SKPhysicsContact *)contact The contact object has two physics bodies: SKPhysicsBody *bodyA; SKPhysicsBody *bodyB; My game will have lots of objects, and of course I can test the categoryBitMask to find out what collided with what. But given that I intend to have many kinds (not more than 32 of course) and might dynamically introduce new types, what's the most elegant way to do dynamic double dispatch to code the logic for collisions, explosions, points scored, etc that will result from

Suppose I have a class hierarchy in Java: interface Item { ... }; class MusicBox implements Item { ... }; class TypeWriter implements Item { ... }; class SoccerBall implements Item { ... }; and I have another class in the same package: class SpecialItemProcessor { public void add(Item item) { /* X */ } } where I want to do something different for each item type, but I don't want to define that action in the different Item classes ( MusicBox , TypeWriter , SoccerBall ). One way to handle this is: class SpecialItemProcessor { public void add(Item item) { if (item instanceof MusicBox) { MusicBox

I'm looking for a way to add an EventListener which will automatically removes itself after the first time it fires, but I can't figure a way of doing this the way I want to. I found this function ( here ) : public class EventUtil { public static function addOnceEventListener(dispatcher:IEventDispatcher,eventType:String,listener:Function):void { var f:Function = function(e:Event):void { dispatcher.removeEventListener(eventType,f); listener(e); } dispatcher.addEventListener(eventType,f); } } But instead of having to write : EventUtil.addOnceEventListener( dispatcher, eventType, listener ); I

Using python3.4. Here I want use singledispatch to dispatch different type in __mul__ method . The code like this : class Vector(object): ## some code not paste @functools.singledispatch def __mul__(self, other): raise NotImplementedError("can't mul these type") @__mul__.register(int) @__mul__.register(object) # Becasue can't use Vector , I have to use object def _(self, other): result = Vector(len(self)) # start with vector of zeros for j in range(len(self)): result[j] = self[j]*other return result @__mul__.register(Vector) # how can I use the self't type @__mul__.register(object) # def _

I have to delete an object of an array every now and then, when I do it I get this error. Collection < CALayerArray: 0xc4f3b20> was mutated while being enumerated The error appears on this method, which is the accesor of the Array: - (NSArray *)occupantsArray { if (dispatch_get_current_queue() == moduleQueue) { return occupantsArray; } else { __block NSArray *result; dispatch_sync(moduleQueue, ^{ //ON THIS LINE result = [occupantsArray copy]; }); return [result autorelease]; } } As you can see Im taking care of not returning the original array but a copy, but it still crashes. Also the method

I would like to use a single domain as a Staging Environment for multiple flask applications that will eventually run on their own domains. Something like: example_staging.com/app1 example_staging.com/app2 example_staging.com/app3 where: example_staging.com/app1 acts same as app1.example_staging.com example_staging.com/app2 acts same as app2.example_staging.com example_staging.com/app3 acts same as app3.example_staging.com or: example_staging.com/app1 acts same as app1.com example_staging.com/app2 acts same as app2.com example_staging.com/app3 acts same as app3.com Starter app: from flask