抽象类继承另一个抽象类问题

Question

I have an inheritance schema like below:

public abstract class BaseAttachment
{
    public abstract string GetName();
}

public abstract class BaseFileAttachment:BaseAttachment
{
    public abstract string GetName();
}

public class ExchangeFileAttachment:BaseFileAttachment
{
    string name;
    public override string GetName()
    {
        return name;
    }
}

I basically want to call GetName() method of the ExchangeFileAttachment class; However, the above declaration is wrong. Any help with this is appreciated. Thanks

Answer 1

The two immediate problems I see is that your final ExchangeFileAttachment class is declared abstract , so you'll never be able to instantiate it. Unless you have another level of inheritance you are not showing us, calling it will not be possible - there's no way to access it. The other problem is that BaseFileAttachment has a property that is hiding the GetName() in BaseAttachment . In the structure you are showing us, it is redundant and can be omitted. So, the 'corrected' code would look more like:

public abstract class BaseAttachment
{
    public abstract string GetName();
}

public abstract class BaseFileAttachment : BaseAttachment
{
}

public class ExchangeFileAttachment : BaseFileAttachment
{
    string name;
    public override string GetName()
    {
        return name;
    }
}

I put corrected in quotes because this use-case still does not make a ton of sense so I'm hoping you can give more information, or this makes a lot more sense on your end.

Answer 2

Just remove the redeclaration from BaseFileAttachment :

public abstract class BaseFileAttachment : BaseAttachment
{
}

BaseFileAttachment already inherits the abstract GetName declaration from BaseAttachment . If you really want to mention it again in BaseFileAttachment , use the override keyword:

public abstract class BaseFileAttachment : BaseAttachment
{
    public override abstract string GetName(); // that's fine as well
}