C#: System.Object vs Generics

I'm having a hard time understanding when to use Object (boxing/unboxing) vs when to use generics.

For example:

public class Stack 
{
    int position;
    object[] data = new object[10];
    public void Push (object o) { data[position++] = o; }
    public object Pop() { return data[--position]; }
}

VS.

public class Stack<T>
{ 
  int position; 
  T[] data = new T[100]; 
  public void Push(T obj)  {data[position++] = obj; }
  public T Pop() { return data[--position]; }
 }

Which one should I use and under what conditions? It seems like with the System.Object way I can have objects of all sorts of types currently living within my Stack. So wouldn't this be always preferable? Thanks!

c# generics object

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1 Answer

A lot of people have recommended using generics, but it looks like they all miss the point. It's often not about the performance hit related to boxing primitive types or casting, it's about getting the compiler to work for you.

If I have a list of strings, I want the compiler to prove to me that it will always contain a list of strings. Generics does just that - I specify the intent, and the compiler proves it for me.

Ideally, I would prefer an even richer type system where you could say for example that a type (even if it was a reference type) could not contain null values, but C# does unfortunately not currently offer that.

answered 2010-12-12T22:06:32.260

C#: System.Object vs Generics

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