Question

The title may be unclear, but please look at the pattern below

public abstract class Animal
{

    public abstract Dog GetDog { get; }

    public abstract Cat GetCat { get; }

}

public class Dog : Animal
{

    public override Dog GetDog {
        get { return this; }
    }

    public override Cat GetCat {
        get { return null; }
    }

}

Is this considered a bad practice to have properties in the base class, return derived types. Or should I do something like

public abstract AnimalTypeEnum AnimalType { get; }

EDIT: Based on the comments, I guess I should be more clear on what I am trying to achieve. A new instance of the Dog or Cat class would be created by a separate function based on certain criteria and would then return Animal type to the caller. The calling method would check the type of the returned instance and use it accordingly.

public Animal CreateAnimal(string path)
{

    //Process the document in path and create either a new instance of dog or cat

    Dog dg = new Dog();

    return dg;

}

Answer 1

The calling method would check the type of the returned instance and use it accordingly.

There’s your problem. It’s code smell to need to do that. You should be able to treat whatever it is as just an object, rather than treating dogs and cats differently.

If you need to display the content of either animal, then override the ToString method on both classes and just call ToString on animal. If you need to know the name of the dog or cat then add a Name property to Animal. If at all possible you should be using polymorphism here so that whatever is using the object treads it as just an Animal and simply involves different things happening as a result of different implementations of the same method.

If you really, really do need to know whether the Animal is a Dog or a Cat then you can use the is or as operators; you don’t need to add all of the code that you’ve shown in the OP.