CODEWITHSUNDEEP
c#genericsinterface
Bartek Wójcik
Bartek Wójcik

Reputation: 425

Interfaces With generic factory

i'm trying to do fancy stuff like this:

i have following code: 

public interface IMyInterface
    {
      void Method1();
    }

  public interface IClassFactory
  {
      object GetObject();
  }

  public interface IGenericClassFactory<T> where T: IMyInterface
  {
       T GetObject();
  }

public class MyClass : IMyInterface
    {
        public void Method1()
        {
            Console.WriteLine("Medota 1");
        }

    }

    public class MyFactory : IClassFactory
    {
         public object GetObject()
        {
            return new MyClass();
        }
    }

    public class MyGenericFactory<T> : IGenericClassFactory<T> where T : IMyInterface, new()
    {
        public T GetObject()
        {
           // T t = new T();
            //return t;
            //var ctor = typeof(T).GetConstructor(new Type[0]);//1] { typeof(int) });
            //if (ctor != null)
            //{
            //    return (T)ctor.Invoke(new object[0]); // new object[1] { 5});
            //    //return Activator.CreateInstance<T>(); //to samo co wyzej tylko nie jest bezpieczne
            //}
            //throw new InvalidOperationException("T nie posiada domyślnego konstruktora");
           // return Activator.CreateInstance<T>(); //bez parametrów 
           // return (T)Activator.CreateInstance(typeof(T), 5, "EOG", new object()); // z parametrami
            return new T();

        }
    }




 static void Main(string[] args)
        {
            IClassFactory factory;
            factory = new MyFactory();

            IGenericClassFactory<IMyInterface> genFactory;
            genFactory = new MyGenericFactory<MyClass>(); //Do not compile!

            MyClass obj = genFactory.GetObject() as MyClass;

            obj.Method1();
            Console.ReadKey();
        }

I can do this like:

 IGenericClassFactory<IMyInterface> genFactory;
            genFactory = new MyGenericFactory<MyClass>();

//so i can chose object to create

but i think it is pointless because i want to have Factory of more then one object. Can u help me?

Thx in advance

Upvotes: 1

Views: 144

Answers (1)

Paweł Bejger
Paweł Bejger

Reputation: 6366

You should not make your factory class generic but the method GetObject should be generic: 

public T GetObject<T>() where T: IMyInterface, new()

Then:

 static void Main(string[] args)
 {
      var factory = new MyFactory();
      var obj = factory.GetObject<MyClass>();

      obj.Method1();
      Console.ReadKey();
 }

So all in all you should get rid of your generic code and simply modify your MyFactory class

public class MyFactory : IClassFactory
{
     public T GetObject<T>()
    {
        //TODO - get object of T type and return it
        return new T();
    }
}

By the way - I am not sure what is the purpose of having this generic implementation? Does it make any sense from the perspective of the usage of Factory pattern?

Upvotes: 2

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