![Factory: example
public interface IDrink
{
string GetDrinkName();
}
public class Beer : IDrink
{
public string GetDrinkName()
{
return "Hoegaarden";
}
}
public class Whiskey : IDrink
{
public string GetDrinkName()
{
return "Jack Daniel's";
}
}
public static class DrinksFactory
{
public static Whiskey GetWhiskey()
{
return new Whiskey();
}
public static Beer GetBeer()
{
return new Beer();
}
}
class Program
{
static void Main(string[] args)
{
var drink = DrinksFactory.GetBeer();
var name = drink.GetDrinkName();
Console.WriteLine(name);
}
}](https://image.slidesharecdn.com/di-151007095504-lva1-app6891/85/IoC-and-Dependency-Injection-5-320.jpg)
![Service Locator: example
public class DrinksLocator
{
private IDictionary<object, object> _services;
public DrinksLocator()
{
_services = new Dictionary<object, object>();
}
public void RegisterDrink<TKey,TValue>() where TValue : new()
{
_services.Add(typeof(TKey), new TValue());
}
public T ResolveDrink<T>()
{
return (T) _services[typeof (T)];
}
}
class Program
{
static DrinksLocator _drinksLocator = new DrinksLocator();
static void Configuration()
{
_drinksLocator.RegisterDrink<IWhiskey, Whiskey>();
_drinksLocator.RegisterDrink<IBeer, Beer>();
}
static void Main(string[] args)
{
Configuration();
var drink = _drinksLocator.ResolveDrink<IWhiskey>();
var name = drink.GetDrinkName();
Console.WriteLine(name);
}
}
public interface IDrink
{
string GetDrinkName();
}
internal interface IBeer : IDrink
{
}
internal interface IWhiskey : IDrink
{
}
public class Beer : IBeer
{
public string GetDrinkName()
{
return "Hoegaarden";
}
}
public class Whiskey : IWhiskey
{
public string GetDrinkName()
{
return "Jack Daniel's";
}
}](https://image.slidesharecdn.com/di-151007095504-lva1-app6891/85/IoC-and-Dependency-Injection-7-320.jpg)
IoC and Dependency Injection
- 1. IoC and Dependency injection itself
- 2. Discussion • Why do we need software development patterns? • What problems does it solves?
- 3. Inversion of control (IoC) Implementation techniques: • Factory • Service Locator • Dependency Injection (DI)
- 4. Factory, Abstract factory • Used to create objects. • Created object can be of different types.
- 5. Factory: example public interface IDrink { string GetDrinkName(); } public class Beer : IDrink { public string GetDrinkName() { return "Hoegaarden"; } } public class Whiskey : IDrink { public string GetDrinkName() { return "Jack Daniel's"; } } public static class DrinksFactory { public static Whiskey GetWhiskey() { return new Whiskey(); } public static Beer GetBeer() { return new Beer(); } } class Program { static void Main(string[] args) { var drink = DrinksFactory.GetBeer(); var name = drink.GetDrinkName(); Console.WriteLine(name); } }
- 6. Service Locator (SL) Service – can be considered as an object that can do something for you as a service. • Service locator returns objects that already exist.
- 7. Service Locator: example public class DrinksLocator { private IDictionary<object, object> _services; public DrinksLocator() { _services = new Dictionary<object, object>(); } public void RegisterDrink<TKey,TValue>() where TValue : new() { _services.Add(typeof(TKey), new TValue()); } public T ResolveDrink<T>() { return (T) _services[typeof (T)]; } } class Program { static DrinksLocator _drinksLocator = new DrinksLocator(); static void Configuration() { _drinksLocator.RegisterDrink<IWhiskey, Whiskey>(); _drinksLocator.RegisterDrink<IBeer, Beer>(); } static void Main(string[] args) { Configuration(); var drink = _drinksLocator.ResolveDrink<IWhiskey>(); var name = drink.GetDrinkName(); Console.WriteLine(name); } } public interface IDrink { string GetDrinkName(); } internal interface IBeer : IDrink { } internal interface IWhiskey : IDrink { } public class Beer : IBeer { public string GetDrinkName() { return "Hoegaarden"; } } public class Whiskey : IWhiskey { public string GetDrinkName() { return "Jack Daniel's"; } }
- 8. Dependency Injection (DI) • Provides you any object (service) of any type whenever it’s needed. • You don’t care about it’s creation and implementation.
- 9. DI vs. SL • The main difference is how the dependencies are located, in Service Location client code request the dependencies , in DI we use container to create all of objects and it injects dependency as constructor parameters (or properties)
- 11. DI: pros • Code is readable and maintainable • Injected class is a standalone module • Configurability. Can be even configured externally. • Object lifetime management • Testability
- 12. DI: cons • It requires you to understand how it works. • Debugging. You might need a reflector
- 13. DI frameworks in .NET • Autofac - http://autofac.org/ • Ninject - www.ninject.org • ASP.NET vNext supports DI out of the box
- 14. JavaScript & Dependency Injection • Angular - https://docs.angularjs.org/guide/di • Ember - http://guides.emberjs.com/v1.10.0/understanding- ember/dependency-injection-and-service-lookup/ • Node.js - https://github.com/vojtajina/node-di