Add registration of components through factory methods

A basic version of Bean factories from the Spring framework

source/poodinis/context.d

@@ -14,7 +14,27 @@
 module poodinis.context;
 
 import poodinis.container;
+import poodinis.registration;
+
+import std.traits;
 
 class ApplicationContext {
 	public void registerDependencies(shared(DependencyContainer) container) {}
 }
+
+/**
+* A component annotation is used for specifying which factory methods produce components in
+* an application context.
+*/
+struct Component {}
+
+public void registerContextComponents(ApplicationContextType : ApplicationContext)(ApplicationContextType context, shared(DependencyContainer) container) {
+	import std.stdio;
+	foreach (member ; __traits(allMembers, ApplicationContextType)) {
+		static if (hasUDA!(__traits(getMember, context, member), Component)) {
+			auto factoryMethod = &__traits(getMember, context, member);
+			auto registration = container.register!(ReturnType!factoryMethod);
+			registration.instanceFactory = new InstanceFactory(registration.instantiatableType, CreatesSingleton.yes, null, factoryMethod);
+		}
+	}
+}

test/poodinis/contexttest.d

@@ -5,8 +5,50 @@
  * The full terms of the license can be found in the LICENSE file.
  */
 
-import poodinis.context;
+import poodinis;
+
+import std.exception;
 
 version(unittest) {
 
+	class Banana {
+		public string color;
+
+		this(string color) {
+			this.color = color;
+		}
+	}
+
+	class Apple {}
+
+	class TestContext : ApplicationContext {
+
+		@Component
+		public Banana banana() {
+			return new Banana("Yellow");
+		}
+
+		public Apple apple() {
+			return new Apple();
+		}
+	}
+
+	//Test register component registrations from context
+	unittest {
+		shared(DependencyContainer) container = new DependencyContainer();
+		auto context = new TestContext();
+		context.registerContextComponents(container);
+		auto bananaInstance = container.resolve!Banana;
+
+		assert(bananaInstance.color == "Yellow");
+	}
+
+	//Test non-annotated methods are not registered
+	unittest {
+		shared(DependencyContainer) container = new DependencyContainer();
+		auto context = new TestContext();
+		context.registerContextComponents(container);
+		assertThrown!ResolveException(container.resolve!Apple);
+	}
+
 }