Question

I want to copy values from one object to another object. Something similar to pass by value but with assignment.

For example:

PushPin newValPushPin = oldPushPin; //I want to break the reference here.

I was told to write a copy constructor for this. But this class has a lot of properties, it will probably take an hour to write a copy constructor by hand.

1. Is there a better way to assign an object to another object by value?
2. If not, is there a copy constructor generator?

Note: ICloneable is not available in Silverlight.

Answer 1

If you can mark the object that is to be cloned as Serializable then you can use in-memory serialization to create a copy. Check the following code, it has the advantage that it will work on other kinds of objects as well and that you don’t have to change your copy constructor or copy code each time an property is added, removed or changed:

    class Program
    {
        static void Main(string[] args)
        {
            var foo = new Foo(10, "test", new Bar("Detail 1"), new Bar("Detail 2"));

            var clonedFoo = foo.Clone();

            Console.WriteLine("Id {0} Bar count {1}", clonedFoo.Id, clonedFoo.Bars.Count());
        }
    }

    public static class ClonerExtensions
    {
        public static TObject Clone<TObject>(this TObject toClone)
        {
            var formatter = new BinaryFormatter();

            using (var memoryStream = new MemoryStream())
            {
                formatter.Serialize(memoryStream, toClone);

                memoryStream.Position = 0;

                return (TObject) formatter.Deserialize(memoryStream);
            }
        }
    }

    [Serializable]
    public class Foo
    {
        public int Id { get; private set; }

        public string Name { get; private set; }

        public IEnumerable<Bar> Bars { get; private set; }

        public Foo(int id, string name, params Bar[] bars)
        {
            Id = id;
            Name = name;
            Bars = bars;
        }
    }

    [Serializable]
    public class Bar
    {
        public string Detail { get; private set; }

        public Bar(string detail)
        {
            Detail = detail;
        }
    }