added DCI.ts

Author: mbrowne

samples/dci/DCI.ts

@@ -0,0 +1,33 @@
+export class Context
+{
+	//For plain JS version
+	//Returns a constructor function to instantiate a new context.
+	//In the future it may also inherit some utility methods that are common to all contexts.
+	//
+	//It will check whether the passed callback function has a bindRoles() method, and if so,
+	//any constructor arguments will be passed to bindRoles(). If the passed callback does not
+	//have a bindRoles() method, then the roles should be bound at the top of the callback function.
+	//
+	//bindRoles() is useful for the case where you want to be able to re-bind the roles on an existing
+	//context object.
+	//
+	static extend(callback): any {
+		return function(...args : any[]) {
+			//We always pass the parameters to the passed function (callback) because
+			//we can't check whether or not a bindRoles() method exists until after we've
+			//instantiated the context object.
+			//The ContextConstructor function is needed so that we can pass constructor arguments dynamically
+			//(see http://stackoverflow.com/a/13931627/560114)
+			var ContextConstructor: any = function() {
+				return callback.apply(this, args);
+			}
+			ContextConstructor.prototype = callback.prototype;
+			
+			var context = new ContextConstructor();
+			context.constructor = callback;
+			
+			if (context.bindRoles) context.bindRoles.apply(context, arguments);
+			return context;
+		}
+	}
+}