unity-container Getting started with unity-container Constructor Injection

Example

interface IService
{
    void ProcessRequest();
}

interface IRepository
{
    IEnumerable<string> GetData();
}

class HelloWorldRepository : IRepository
{
    public IEnumerable<string> GetData()
    {
        return new[] { "Hello", "World" };
    }
}

class HelloWorldService : IService
{
    private readonly IRepository repo;
    public HelloWorldService(IRepository repo)
    {
        this.repo = repo;
    }
    public void ProcessRequest()
    {
        Console.WriteLine(String.Join(" ", this.repo.GetData()));
    }
}

class Program
{
    static void Main(string[] args)
    {
        var container = new UnityContainer()
            .RegisterType<IRepository, HelloWorldRepository>()
            .RegisterType<IService, HelloWorldService>();

        //Unity automatically resolves constructor parameters that knows about.
        //It will return a HelloWorldService with a HelloWorldRepository
        var greeter = container.Resolve<IService>();
        //Outputs "Hello World"
        greeter.ProcessRequest();            

        Console.ReadLine();
    }
}