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copied!<p>You can create a <code>DynamicObject</code> that forwards the calls it receives to a list of targets, in a chain of responsibility style (note that polymorphic dispatch also works like this - from the most derived class upwards):</p> <pre><code>public class Composition : DynamicObject { private List<object> targets = new List<object>(); public Composition(params object[] targets) { AddTargets(targets); } protected void AddTargets(IEnumerable<object> targets) { this.targets.AddRange(targets); } public override bool TryInvokeMember( InvokeMemberBinder binder, object[] args, out object result) { foreach (var target in targets) { var methods = target.GetType().GetMethods(); var targetMethod = methods.FirstOrDefault(m => m.Name == binder.Name && ParametersMatch(m, args)); if (targetMethod != null) { result = targetMethod.Invoke(target, args); return true; } } return base.TryInvokeMember(binder, args, out result); } private bool ParametersMatch(MethodInfo method, object[] args) { var typesAreTheSame = method.GetParameters().Zip( args, (param, arg) => param.GetType() == arg.GetType()); return typesAreTheSame.Count() == args.Length && typesAreTheSame.All(_=>_); } } </code></pre> <p>Note that you'd also want to implement delegation for properties (<code>TryGetMember</code> and <code>TrySetMember</code>), indexers (<code>TryGetIndex</code> and <code>TrySetIndex</code>) and operators (<code>TryBinaryOperation</code> and <code>TryUnaryOperation</code>).</p> <p>Then, given a set of classes:</p> <pre><code>class MyClass { public void MyClassMethod() { Console.WriteLine("MyClass::Method"); } } class MyOtherClass { public void MyOtherClassMethod() { Console.WriteLine("MyOtherClass::Method"); } } </code></pre> <p>You can "blend" them all together:</p> <pre><code>dynamic blend = new Composition(new MyClass(), new MyOtherClass()); blend.MyClassMethod(); blend.MyOtherClassMethod(); </code></pre> <p>You can also extend the dynamic object to use classes' attributes or other kinds of annotations to look for mixins. For example, given this annotation interface:</p> <pre><code>public interface Uses<M> where M : new() { } </code></pre> <p>You can have this <code>DynamicObject</code>:</p> <pre><code>public class MixinComposition : Composition { public MixinComposition(object target) : base(target) { AddTargets(ResolveMixins(target.GetType())); } private IEnumerable<object> ResolveMixins(Type mainType) { return ResolveMixinTypes(mainType). Select(m => InstantiateMixin(m)); } private IEnumerable<Type> ResolveMixinTypes(Type mainType) { return mainType.GetInterfaces(). Where(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(Uses<>)). Select(u => u.GetGenericArguments()[0]); } private object InstantiateMixin(Type type) { return Activator.CreateInstance(type); } } </code></pre> <p>And create your "blends" like this:</p> <pre><code>class MyMixin { public void MyMixinMethod() { Console.WriteLine("MyMixin::Method"); } } class MyClass : Uses<MyMixin> { public void MyClassMethod() { Console.WriteLine("MyClass::Method"); } } ... dynamic blend = new MixinComposition(new MyClass()); blend.MyClassMethod(); blend.MyMixinMethod(); </code></pre>

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