Convert/Cast base type to Derived type

Question

I am extending the existing .NET framework class by deriving it. How do I convert an object of base type to derived type?

public class Results { //Framework          


        

Answer 1

As earlier answers have said, you need to instantiate a new instance of MyResults then copy the properties over from your Results object. You asked what a "copy constructor" was - it is just a constructor that takes an object and uses it to populate the object being constructed. For example:

    public class Results
    {
        public string SampleProperty1 { get; set; }
        public string SampleProperty2 { get; set; }
    }

    public class MyResults : Results
    {
        public MyResults(Results results)
        {
            SampleProperty1 = results.SampleProperty1;
            SampleProperty2 = results.SampleProperty2;
        }
    }

A copy constructor is usually more convenient, readable and reusable than using code like this:

MyResults myResults = new MyResults
{
    SampleProperty1 = results.SampleProperty1,
    SampleProperty2 = results.SampleProperty2
};

If there are lots of properties and/or you are making lots of changes to the class you could use reflection (e.g. C# Using Reflection to copy base class properties ) or a tool such as AutoMapper ( http://automapper.codeplex.com ) to copy the properties. But often that can be overkill.