问设计原则

EN

public class Chef : IResturauntWorker 
{
    // This is an example of writing to an interface instead of an
    // an implementation.  Because the Chef class implements the 
    // IResturauntWorker interface, the chef can be swapped in with other
    // resturaunt workers like bussers or waiters.

    public void Chop(Carrot c)
    {
        // code to chop a carrot

        // this is an example of depending on an implementation
        // because Carrot is a concrete class, this method can 
        // only be used with a Carrot
    }

    public void Chop(IVegetable c)
    {
        // code to chop a Vegetable

        // this is an example of depending on an abstraction
        // because IVegetable is a abstraction of an idea 
        // (a vegetable, in this case), this method can be
        // used with any class that implements IVegetable,
        // including carrots, celery, onions, etc.
    }
}