从具有其他类型属性的抽象类继承（.NET 3.5，C＃）

Question

I have 3 following classes:

public class BaseProperty1{
    public string Property1 {get; set;}
}

public class ChildProperty1 : BaseProperty1 {

}

public abstract class Base{
    public abstract BaseProperty1 bp1 {get; set;}
}

I'm trying to derive a following class from Base:

public class Child : Base{
    public ChildProperty1 bp1 {get; set;}
}

But I'm getting an error that "set" and "get" methods are not implemented. Is it just the syntax I'm using or my way of thinking is wrong?

Thank you!

Answer 1

You won't be able to use Auto Properties since you have to match the type of the base class exactly. You'll have to go the old fashioned way:

public abstract class Child : Base
{
    private ChildProperty1 _bp1;

    public BaseProperty1 bp1
    {
        get { return _bp1; }

        // Setter will be tricky. This implementation will default to null
        // if the cast is bad.
        set { _pb1 = value as ChildProperty1; }
    }
}

You might also be able to use generics to solve the problem:

public abstract class Parent<TProp> where TProp : BaseProperty1
{
    public abstract T bp1 { get; set; }
}

public abstract class Child : Parent<ChildProperty1>
{
    public ChildProperty1 bp1 { get; set; }
}

Answer 2

If you mark method or property as an abstract , you must implement it in inherited class. You can hide old property (bp1 in Base class) and write new one with another return type like this:

public abstract class Base{
    public BaseProperty1 bp1 {get; set;} //without abstract identifier
}

public class Child : Base
{
       public new ChildProperty1 bp1 { get; set; } // with new modifier
}