Question

Is there a fast way to copy a generic TList?

Copy.Capacity := List.Count;
for Item in List do
  Copy.Add (Item);

is very slow. There seems to be no way to use CopyMemory since I can’t get the memory adress of the internal array (which is obvious from an information hiding viewpoint). I miss something like

List.Copy (Copy);

which uses the knowledge of the internal representation to improve performance. Can it be done?

Answer 1

For the generic TList<T> it is simply not possible to implement the function you want. That’s because copy the contents of T may involve more than a simple memory copy. If T contains any managed types (i.e. strings, interfaces etc.) then the reference counts on those managed objects must be incremented.

• If your T does contain managed types then I doubt that you can do much better then the code you already have.
• If your T does not contain any managed types then a memory copy is viable but you will need to create your own class to encapsulate this list since TList<T> is not appropriate.