quickstart1.md

ComposerCore Sample - Quick Start scenario one

In this sample, you see the minimal way of using ComposerCore to instantiate a component without any dependency injection complexities.

Complete source of this sample

Declare a contract type

Declare a class or interface to be a contract for a component. You use such contracts to look up a component from ComposerCore, that is, when you're looking for some component to provide the services specified by the contract. Use [Contract] meta data attribute on a type to do so.

    [Contract]
    public interface ILogger
    {
        void Log(string log);
    }

Write a component

Implement a concrete class that implements / extends the contract type

    [Component]
    public class DefaultLogger : ILogger
    {
        public void Log(string log)
        {
            Console.WriteLine(log);
        }
    }

Create an instance of ComposerCore and register the component type

ComposerCore is a simple class library, and you can simply instantiate the ComponentContext class to have a new instance of ComposerCore ready to use. Then use the Register method on the instance to introduce component types to ComposerCore.

    var composer = new ComponentContext();
    composer.Register(typeof(DefaultLogger));

ComposerCore will reflect the component type, and discover the provided contracts. After doing so, ComposerCore knows someone who can provide the mentioned contract, so you can ask for it.

Query for the component

Ask ComposerCore that "I want some object who can provide this service" using GetComponent method.

    composer.GetComponent<ILogger>().Log("Hello, compositional world!");

ComposerCore will find the appropriate component type (which is previously registered), instantiate it, initialize it and return it.

ComposerCore will also keep a reference to the component, so that it can respond to the later requests with the same instance. So if you ask for the component again, the same instance is returned. (You can change this behavior by specifying component cache settings.)