Create copy of List without reference to original

Question

I know this has been covered before but from what I understand in the post this should work.

Example code:

I have a custom type:

public class MyType
{
    public List<MySubType> Movie { get; set; }
    public List<int> Ranks { get; set; }
    public string Location { get; set; }
    public string Released { get; set; }
}

I then create a List of this type

List<MyType> myMovies = new List<MyType>();

Later in the code I need to create a copy of this list and change it without affecting the original.

List<MyType> copyMovies = new List<MyType>(myMovies);

But now if I remove from the list within copyMovies

copyMovies.Movie.RemoveAt(x);

It removes from both lists

Unless I am totally missing something this post suggests I should be able to change the copy list without it effecting the original.

Answer 1

You can simply call ToList() on your original list, and it will generate a copy.

Answer 2

I am pretty sure your code should work. MSDN says about the constructor:

Initializes a new instance of the List class that contains elements copied from the specified collection and has sufficient capacity to accommodate the number of elements copied.

Are you sure you didn't miss anything?

EDIT:

You did miss something... Your example was wrong and misleading. Your edit showed you try to delete an item from the list INSIDE your type. These are not copied / cloned when copying the parent class. You need to Clone each and every single property of your class. Take a look at Deep cloning objects.

Answer 3

Well if you think that copyMovies.RemoveAt(x) instead of copyMovies.Movie.RemoveAt(x) is only SLIGHTLY MISLEADING then sorry my friend, but you're just wasting our time here.

Internal list has been copied by a reference, so you need to copy the whole internal list instead, f.e:

List<MyType> copyMovies = new List<MyType>(myMovies.Select (m => new MyType()
{
    Movie = new List<MySubType>(m.Movie),
    Ranks = m.Ranks,
    Location = m.Location,
    Released = m.Released
}));

or

List<MyType> copyMovies = myMovies.Select (m => new MyType()
{
    Movie = new List<MySubType>(m.Movie),
    Ranks = m.Ranks,
    Location = m.Location,
    Released = m.Released
}).ToList();

Or with the copy constructor:

//in MyType definition
public MyType(MyType objectToCopy)
{
    Movie = new List<MySubType>(m.Movie);
    Ranks = m.Ranks;
    Location = m.Location;
    Released = m.Released;
}

and then you'd be able to use it this way:

List<MyType> copyMovies = myMovies.Select (m => new MyType(m));