Covariance Without Generics
time to read 2 min | 263 words

A few days ago I asked why you can't treat IList<String> as IList<Object>, Wesner Moise commented with the explanation, and Mitch Denny has a post with a fuller explanation. One interesting thing that came up via a comment from Tomer Gabel was that the following code is legal:

static void Main(string[] args)
{
 object[] array = GetList();
 array[2] = 1;
}
public static object[] GetList()
{
 return new string[10];
}

 This suffer from exactly the same problem that you get with generics. In fact, while the code compiles, trying to run it results in ArrayTypeMismatchException. I never dug deep enough into the runtime so I could tell you how arrays are implemented, but I think that they are just getting special threatment from the runtime. Any Rotor hackers out there that can comment on that?

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