C#:关于接口(interface)、实现和继承的混淆

Question

我想知道要走什么路，如果我需要发布数据接口(interface)但想在内部使用它们和扩展的计算属性。为了更清楚:

// The public interface
public interface IData
{
    int Property { get; }
}

// The internal interface
internal interface IExtendedData : IData
{
    int ExtendedProperty { get; }
}

// The assumed implementation of someone using my interface
public class Data : IData
{
    public Data(int a)
    {
        Property = a;
    }

    public int Property
    {
        get;
        private set;
    }

    public override string ToString()
    {
        return Property.ToString();
    }
}

// My implementation
internal class ExtendedData : IExtendedData
{
    public ExtendedData(int a)
    {
        Property = a;
    }

    public int Property
    {
        get;
        private set;
    }

    public int ExtendedProperty
    {
        get
        {
            return 2 * Property;
        }
    }

    public override string ToString()
    {
        return Property.ToString() + ExtendedProperty.ToString();
    }
}

// publicated by me, for the person who uses my dll
public static class Calculations
{
    public static int DoSomeCalculation(IData data, int parameter)
    {
        // This probably don't work, but maybe shows what I want to do
        IExtendedData tempData = (ExtendedData)data;
        return tempData.ExtendedProperty * parameter;
    }
}

我真的很沮丧，因为我觉得缺少一些基本的编程技能。

Answer 1

您可以通过将 ExtendedData 实现为实现 IData 的类的包装器来解决此问题

internal class ExtendedData : IExtendedData
{

    private IData data;
    public ExtendedData(IData data)
    {
        this.data = data;
    }

    public int Property
    {
        get { return data.Property; }
        private set { data.Property = value; }
    }

    public int ExtendedProperty
    {
        get
        {
            return 2 * Property;
        }
    }    
}

并在 DoSomeCalculation 中使用它，例如

 IExtendedData tempData = new ExtendedData(data);