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Dependency Injection with Simple Injector

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Before some I have written a blog post about how to do dependency injection with StructureMap. In this post we are going to learn Simple Injector IOC library and how we can do dependency injection with Simple Injector.

About Simple Injector:

Simple Injector is a open source dependency injection library developed with C#. Followings are few characteristics of Simple Injector.
  • Simple Injector is very simple to use dependency injection library support .NET 4+ framework, Silverlight 4+, Windows Phone 8, Windows 8 Including Universal apps and Mono.
  • Simple Injector is easily integrated with frameworks like ASP.NET Web Forms, ASP.NET MVC, ASP.NET Web API, WCF and many more.
  • It’s free and always be free. Published under MIT license.
  • Simple Injector is highly optimized for performance and concurrent use.
  • Simple Injector is thread safe and lock free design.
  • Simple Injector has great support for generics and used lot of things of generics then any other dependency injection libraries.
  • Simple Injector has a powerful diagnostic system.Currently it offers following validations
    • Lifestyle Mismatch
    • Short Circuit Dependencies
    • Potential Single Responsibility violations
    • Container Register Types
  • Simple Injector is amazingly fast.
  • Simple Injector is developed using Modern proven development practices such as TDD and Solid Design Principals.

You can find more information about Simple Injector from the following links.
https://simpleinjector.org/index.html
https://simpleinjector.codeplex.com/wikipage?title=Using%20the%20Simple%20Injector&referringTitle=Documentation

Dependency Injection Example with Simple Injector:

In this post we are going to use same example that I have used for StructureMap post. So let’s create a console application for this.

simple-injector-sample-app

Now it’s time to add Simple Injector to the project. You can use it via following nuget package.
Install-Package SimpleInjector
After adding nuget package it’s time to write some code. I am going to create a shopping cart to represent some of scenarios.
namespace SimpleInjectorDemo
{
    public interface IOrder
    {
        void Process();
    }
}
Here I have creaed IOrder interace which will be implemented by PurchaseOrder class.
using System;

namespace SimpleInjectorDemo
{
    public class PurchaseOrder : IOrder
    {
        public void Process()
        {
            Console.WriteLine("Purchase Order processed");
        }
    }
}
Now it’s time to write our shopping cart code. Following is a code for that.
namespace SimpleInjectorDemo
{
    public class ShoppingCart
    {
        private readonly IOrder _order;

        public ShoppingCart(IOrder order)
        {
            _order = order;
        }

        public void CheckOut()
        {
            _order.Process();
        }
    }
}
If you see whole source code carefully you can see that ShoppingCart class requires a IOrder object to construct object of ShoppingCart class. We are going to inject this value with the help of Simple Injector dependency injection library.
namespace SimpleInjectorDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            var container = new SimpleInjector.Container();
            container.Register<IOrder,PurchaseOrder>();

            var shoppingCart = container.GetInstance<ShoppingCart>();
            shoppingCart.CheckOut();
        }
    }
}
Here you can see that I have created a container and use register method to configure a container. I have mapped IOrder to PurchaseOrder so that whenever any Instance of IOrder require it will create a object of PurchaseOrder class. Then I will call method to get a instance of Shopping cart and call a method to checkout.

Now let’s run application and following is a output as expected.

depedency-injection-with-simple-injector
That’s it. Hope you like it. Stay tuned fore more!!

You can find complete source code of above blog post at following location on github. https://github.com/dotnetjalps/SimpleInjectorSimpleExample

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Published at DZone with permission of Jalpesh Vadgama, DZone MVB. See the original article here.

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