private Animal returnNewAnimal(string name, string kind)
{
Animal animal = null;
switch (kind)
{
case "lion":
animal = new LionFactory().CreateAnimal(name);
break;
case "tiger":
animal = new TigerFactory().CreateAnimal(name);
break;
case "elephant":
animal = new ElephantFactory().CreateAnimal(name);
break;
case "bear":
animal = new BearFactory().CreateAnimal(name);
break;
case "wolf":
animal = new WolfFactory().CreateAnimal(name);
break;
case "fox":
animal = new FoxFactory().CreateAnimal(name);
break;
}
return(animal);
}
static void Main(string[] args)
{
/**
* TASK 1
* Understanding factory method (Factory Pattern)
* This is creating an interface that will be responsible for
* creating the ideal factory needed given an instance
* upon creating the right factory, the right object will be returned.
* In this case, the IAnimalFactory returns an IAnimal (Dog or Lion) object
* this is through CreateAnimal method of the IAnimalFactory(DogFactory ot LionFactory)
**/
// Factory Method.
IAnimalFactory dogFactory = new DogFactory();
IAnimal dog = dogFactory.CreateAnimal();
IAnimalFactory lionFactory = new LionFactory();
IAnimal lion = lionFactory.CreateAnimal();
//---------------------------------------
/**
* Task 2
* Manual Inversion of Control using Depedency Injection
* Dependency injection allows applications to be loosely coupled
* It helps to support plugable code.
* The main objective is limit the use of the keyword 'new'
* meaining creating a new instance of an object within another class
* if an object is instanciated within another class, that forces dependencies
* meaning the object that is responsible for instanciating another object is
* strongly dependent on the object to be instanciate.
* this can make things difficult when new functionalities are to be added
* object implementation can change
*
* In the next 3 lines of code below,
* the program handle is injected with a specific object type,
* this can change from DogFactory to LionFactory,
* but the implementation of ProgramHandle does not have to change,
* it will know how to create an animal given the type of object it is provided
* in the constructor. Ths is known as the Constructor Injection
* (There are other types such as Property Injection or Method Injection)
**/
var programHandler = new ProgramHandler(new DogFactory());
IAnimal manuallyCreatedAnimalDependencyInjection = programHandler.CreateAnimal();
/**
* Task 3
* Using DI container (Unity)
* We use DI container's so we dont have to keep writting manual DI code
* First we create a our bindings, I have done this in ProgramModule
* by binding the interface to the concrete class.
* Then get the right interface of the object passed into the kernel line 73
* the returned object is what we use in calling CreateAnimal method.
*/
IKernel kernel = new StandardKernel();
kernel.Load(Assembly.GetExecutingAssembly());
IAnimalFactory kernelAnimalFactory = kernel.Get <DogFactory>();
var programHanderFromKernel = new ProgramHandler(kernelAnimalFactory);
IAnimal animalFromKernel = programHanderFromKernel.CreateAnimal();
/**
* Reflection
* This is just a basic explanation of reflection,
* it is when an object checks it's own metadata for information
* in order to be able to carry out some sort of behaviour.
* In this case, each objec is reflection of it's self
* so that we can use the type in a string to be displayed in our output.
*/
WriteLine(dog.GetType(), dog);
WriteLine(lion.GetType(), lion);
WriteLine(manuallyCreatedAnimalDependencyInjection.GetType(),
manuallyCreatedAnimalDependencyInjection);
WriteLine(animalFromKernel.GetType(), animalFromKernel);
Console.ReadLine();
}
