C# 派生 class 初始化

Question

My C# code scenario:

public class BaseClass 
{
       public int A;
       public float B;
       //a multitude of other fields
       public string Y;
};

public class DerivedClass:BaseClass {
       public string Z;
       public DerivedClass (BaseClass b) {
       //??
       }
}

I want to write this DerivedClass constructor without explicit memberwise copy. In C++, a default BaseClass constructor would do it for me. Thank you in advance.

Answer 1

You're asking if there's an easy way to create a copy constructor in C#.

No, there is no way to do this without specifying the fields you want to copy in one of the constructor explicitly.

see the docs for more info.

Answer 2

I don't know an easy way to write fully functional copy constructor in c#. So either you implement it in BaseClass manually or you can use reflection to automate it.

Last option would be to try to use Automapper which will have some limitations(but for provided code should work) in terms what it can handle - only public properties/fields will be mapped and implementation will look like this:

public class BaseClass
{
    private static readonly IMapper _mapper;
    static BaseClass()
    {
        var config = new MapperConfiguration(cfg => cfg.CreateMap<BaseClass, BaseClass>());
        _mapper = config.CreateMapper();
    }
    public int A;
    public float B;
    //a multitude of other fields
    public string Y;
    public BaseClass(){}
    public BaseClass(BaseClass b)
    {
        _mapper.Map<BaseClass, BaseClass>(b,this);
    }
};

public class DerivedClass : BaseClass
{
    public string Z;
    public DerivedClass(BaseClass b): base(b)
    {
    }
}