KingAOP

It's an AOP framework which is essentially a free alternative of PostSharp. If you familiar with PostSharp, then you can notice that KingAOP has even the same interfaces to interract with you:)

The concept of aspect-oriented programming (AOP) offers an interesting alternative for the specification of non-functional component properties (such as fault-tolerance properties or timing behaviour), as well as other crosscutting concerns. These are implemented as so-called aspects and at some point "weaved" to the other functional parts of the software.

How it works?

It‘s use a dynamic opportunities of C# 4.0 instead of IL rewriting technique which the PostSharp use. And that brings us to a predictable and clean model. You can look through an AOP weaving stuff in very easy way.

Basic example:

• Implement a hello world aspect.

class HelloWorldAspect : OnMethodBoundaryAspect
{
    public override void OnEntry(MethodExecutionArgs args)
    {
        Console.WriteLine("OnEntry: Hello KingAOP");
    }

    public override void OnExit(MethodExecutionArgs args)
    {
        Console.WriteLine("OnExit: Hello KingAOP");
    }
}

• Add the hello aspect to some class.

class HelloWorld : IDynamicMetaObjectProvider
{
    [HelloWorldAspect]
    public void HelloWorldCall()
    {
        Console.WriteLine("Hello World");
    }

    public DynamicMetaObject GetMetaObject(Expression parameter)
    {
        return new AspectWeaver(parameter, this);
    }
}

• Enjoy.

dynamic helloWorld = new HelloWorld();
helloWorld.HelloWorldCall();

Logging example:

Using the above studied concept, we will now attempt to develop a simple logger which will use AOP to log information. It’s canonical example of AOP, as without it:). Like with PostSharp we have to inherit from the OnMethoBoundaryAspect and override the OnEntry and OnExit methods.

• Create LoggingAspect.

internal class LoggingAspect : OnMethodBoundaryAspect
{
    public override void OnEntry(MethodExecutionArgs args)
    {
        string logData = CreateLogData("Entering", args);
        Console.WriteLine(logData);
    }

    public override void OnExit(MethodExecutionArgs args)
    {
        string logData = CreateLogData("Leaving", args);
        Console.WriteLine(logData);
    }

    private string CreateLogData(string methodStage, MethodExecutionArgs args)
    {
        var str = new StringBuilder();
        str.AppendLine();
        str.AppendLine(string.Format(methodStage + " {0} ", args.Method));
        foreach (var argument in args.Arguments)
        {
            var argType = argument.GetType();

            str.Append(argType.Name + ": ");

            if (argType == typeof(string) || argType.IsPrimitive)
            {
                str.Append(argument);
            }
            else
            {
                foreach (var property in argType.GetProperties())
                {
                    str.AppendFormat("{0} = {1}; ",
                        property.Name, property.GetValue(argument, null));
                }
            }
        }
        return str.ToString();
    }
}