Question

Given the two classes below, how can I
convert List<Person> to
List<Person2>?

EDIT: This is a fabricated example. The point I’m trying to make is that I can’t modify the Person class, and we’ll know arbitraryNumber when we instantiate List<Person2>.

EDIT2: I know that many of you will find this unbelievable, but this code will be deployed to a Windows-Server-2000 machine, which means that it must work with .NET 2.0. [Yes – I find this to be unbelievable as well.]

public class Person
{
    private string _lastName;
    public string LastName
    {
        get { return _lastName; }
        set { _lastName = value; }
    }

    private string _firstName;
    public string FirstName
    {
        get { return _firstName; }
        set { _firstName = value; }
    }
}

public class Person2 : Person
{
    private readonly int _arbitraryNumber;
    public Person2(int arbitraryNumber)
    {
        _arbitraryNumber = arbitraryNumber;
    }

    public string FullName
    {
        get
        {
            return String.Format("{0}, {1} - {2}", LastName, FirstName, _arbitraryNumber);
        }
    }
}

Answer 1

I think Person2 needs to change to be an adapter. Something like this

public class Person2
{
    private readonly int _arbitraryNumber;
    private readonly Person _person;
    public Person2(Person person, int arbitraryNumber)
    {
        _arbitraryNumber = arbitraryNumber;
        _person = person;
    }

    public string FullName
    {
        get
        {
            return String.Format("{0}, {1} - {2}", _person.LastName, _person.FirstName, _arbitraryNumber);
        }
    }
}

Then the adapter on the collection is easier.

List<Person> persons = new List<Person>();
// put some people in it.
var person2s = persons.Select(p => new Person2(4, p)); // 4 chosen arbitrarily

Or for .NET 2

List<Person2> person2s = new List<Person2>();
foreach (Person p in persons)
{
    Person2 person2 = new Person2(p, 11); // 11 arbitrarily chosen by asking a kid for a number
    person2s.Add(person2);
}