SidekickNet.Aspect.DynamicInheritance 1.0.1

SidekickNet

SidekickNet provides common utilities for .NET (.NET Standard 2.0 and above).

Aspect-oriented Programming

One of the important utilities provided by SidekickNet is Aspect-oriented Programming. There are three projects for AOP:

• Aspect provides the framework and interfaces of AOP. It uses proxy objects for add advices to objects.
  • It doesn't provide implementations of proxy objects and proxy creation, because there are many possible implementations. Two reference implemenations are provided below that can be directly used.
• Aspect.DynamicInheritance implements proxy objects using dynamic inheritance.
  • This implemenation is optimized for performance by generating IL code directly.
• Aspect.SimpleInjector implements automatic proxy creation using SimpleInjector.
  • Dependency Injection is a convenient way of proxy creation. But other implementation are also possible.

AOP Example

Assume we want to log method entrance easily. First, create an "advice" that specifies what to do upon method entrace.

[AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
internal class LoggingAdviceAttribute : AdviceAttribute
{
    public override void Apply(IInvocationInfo invocation)
    {
        // Advice action - log the entrance of the method
        Console.WriteLine($"Entering {invocation.Method.Name}");

        // Continue with the original method
        this.Proceed(invocation);
    }
}

Then, apply the "advice" to the target method.

public class Foo : IFoo
{
    // Adding the advice attribute is enough to automatically run the logging code
    // Note the method must be "virtual" for dynamic inheritance to work
    [LoggingAdvice]
    public virtual void DoSomething()
    {
        // Business logic
    }
}

Finally, register how proxies will be created. In this case we use Simple Injector.

public void Initialize()
{
    // Create the DI container
    var container = new Container();

    // The proxy factory provided by an implementation, such as Dynamic Inheritance
    var proxyFactory = new ProxyFactory();

    // Tell the DI container to create a proxy object when an object is requested
    container.InterceptTarget(
        type => proxyFactory.GetProxyType(type).GetConstructors()[0]);

    // Register the advice in the container
    container.Register<LoggingAdviceAttribute>();

    // Register the regular types
    container.Register<IFoo, Foo>();

    // The "foo" object obtained from the DI container
    // is actually a proxy that will apply the advice and invoke the origianl method
    var foo = container.Get<IFoo>();

    // Print "Entering DoSomething" before actualy do something
    foo.DoSomething();
}

The Aspect.Test unit test project contains more examples, such as advice bundles.

Other Utilities

• Utilities provides common helpers for strings, collections, exceptions, etc.
• Utilities.AspNetCore provides ASP.NET Core helpers, such as YAML (instead of JSON) configuration files.