Aspect Castle Facility

Introduction

The Aspect Castle Facility uses a declarative approach to register interceptors by defining Advices and Pointcuts.

Features

• Declarative approach for applying interceptors.
• No direct interception registration required for each type.
• No proxy object would be created for no matching pointcut.

Examples

Consider the following example. (inspired from AOP introduction of Castle Windsor)

public interface ISomething
    {
        int Augment(Int32 input);
        void DoSomething(String input);
    }

class Something : ISomething
    {
        [Log]
        public int Augment(int input)
        {
            return input + 1;
        }

        public void DoSomething(string input)
        {
            Console.WriteLine("I'm doing something: " + input);
        }
    }

Instead of calling for .Interceptors() while registering the component :

container.Register(
		Component.For<IInterceptor>()
		.ImplementedBy<LogAdvice>()
		.Named("myinterceptor"));

	container.Register(
		Component.For<ISomething>()
		.ImplementedBy<Something>()
		.Interceptors(InterceptorReference.ForKey("myinterceptor")).Anywhere);

You can declaratively intercept method calls :

    var container = new WindsorContainer();
    container.Register(Component.For<ISomething>().ImplementedBy<Something>());

    container.AddFacility<AspectFacility>(x =>

                {
                    x.AddAttributePointcut<LogAttribute, LogAdvice>();
                });

    var something = container.Resolve<ISomething>();
                
    //It's going to get intercepted because of applied Log attribute
    something.Augment(10);

As you can verify the actual implementation of the interceptor is in the LogAdvice class.

This example certifies a couple of things, the first is component registration has been decoupled from Aspect declaration, the other one is that once you remove the LogAttribute, no proxy objects would be created by Castle DynamicProxy and it is not required to change the component registration section anymore.

Here are the simple implementation of the LogAdvice and LogAttribute classes :

 [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
 public sealed class LogAttribute : Attribute
 {
 }

class LogAdvice : AttributeInterceptor<LogAttribute>
    {
        protected override void InnerIntercept(IInvocation invocation)
        {
            Console.WriteLine($"interceptor called before '{invocation.Method.Name}'");
            invocation.Proceed();
            Console.WriteLine($"interceptor called after '{invocation.Method.Name}'");
        }
    }

Predefined pointcuts implemented already are:

• AttributePointcut
• InheritancePointcut

Please look at the sample project for how to use the facility.

Roadmap

• Conducting more predefined pointcuts.

Contribution

Comments, contributions and patches are greatly appreciated.

NuGet Package

• https://www.nuget.org/packages/Castle.Facilities.Aspect/