My name
is
Jon Skeet

removing switch calling function based on object type using polymorphism

I have a piece of code (shown below) where i want to be able to call a function depending on the object type that is passed in, i currently have a switch statement which manages this but it feels kinda dirty to me. What would the best method of refactoring the code to make use of polymorphism to enable me to remove the switch statement?

if (entity != null)    
{
    //Switch based on entity type
    switch (entity.GetType().Name)
    {

        case "Person":

            //Person implementation

            break;
        case "Organisation":
            //Organisation implementation


            break;
        default:
            break;
    }

}

Edit: For clarification of anyone else finding this, i dont have access to the Entity models source, which led me to mark answer as such, if it wasnt for this then i would have marked Jon's answer as correct!

To use polymorphism, you'd introduce an abstract method in whatever the base class is for all your entities:

public abstract class EntityBase
{
    public abstract void GiveMeABetterName();
}

(We don't know what you're trying to do, hence the name...

You'd then implement the method in each of your subclasses (Person, Organization etc). You can then just use:

entity.GiveMeABetterName();

where you currently have your switch block.

Now that isn't always an appropriate option - for example, what you're trying to do may be something outside the domain of your entity (e.g. displaying information in a GUI). If the code for each of those types really doesn't belong in your entities, you could:

Use the visitor pattern, which would work particularly well if there are multiple operations for each entity
Have a Dictionary<Type, Action> or something similar to look up the action to take for each type
Keep your existing approach, but use is or as instead of switch to avoid putting the names as string literals

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