ArrayList deep copy?

I'm looking at using the ArrayList template to generate custom entity collection classes, but am running into a snag - the lack of support for deep copies, which I need for creating original (backup) versions of any template containing one or more collections of other entities.

Oskar,

Look at the CSLA templates. Specifically look at the BusinessBase and BusinessCollectionBase classes. These contain a Clone method that does a deep copy.

HTH!

Slartibartfast
fjord Engineer ;)

Oskar,

The problem is that there's no standardized "deep copy" functionality in the .NET Framework. The standard collection classes don't provide deep copies for the same reason.

Shallow copying is the only thing that's guaranteed to work because you just copy the element references. Anything else has to rely on the assumption that the specific type in question, and any other types it might reference, provides deep copies of itself via ICloneable.Clone (or in some other way).

ICloneable.Clone on any collection template definitely will never do a deep copy, for how then would you create a shallow copy if you wanted one? Providing another method that attempts to call ICloneable.Clone on all the elements would be possible, though.

Browsing the MSDN Library, I see that a couple of types provide a Copy method to make deep copies of themselves. I suppose that would be a possible enhancement for a future release.

Cheers, Chris

Okay, I've thought about it and realized that I need a deep copy anyway, so I'll put it in the next release. The method is named Copy, and it invokes a customizable method on the ItemType elements. The templates detect when you try to deep-copy value types or strings, and do a shallow copy instead automatically.

For dictionary collections, only the values are copied in this way; the keys are always just cloned with a shallow copy. That should work well enough for the majority of cases where the key is a value type or a string, and avoids the pitfall of trying to index a copied dictionary with a key from the original dictionary.

Chris, thanks. Looking forward to the next release.

Oskar

Deep copies for all collection classes are in the new version 1.5.0. Let me know if there are any problems.

Cheers, Chris

A deep copy also seems to be performed in standard C# statements while performing a memberwise copy like so:
(assuming that ArrayListToCopy contains the original data and u cast the type back to the original content of the array)

ArrayList arrayToCopyTo = new ArrayList();
for(int i = 0; i < ArrayListToCopy.Length; i++)
{
arrayToCopyTo.Add((Type) ArrayListToCopy);
}

I used above successfully but then when we wrapped my solution into another project which is a COM wrapper for our project. It interfaces to a VB6 project that needs to use ours. However once launched there is no interaction until we exit.

I am getting an error on the Deserialization. I am using the exact function above. The error is "Binary Formatter Version incompatibility. Expected version 1.0. Received version 170173..."

Any thoughts on how to get around this? Worked great til we integrated.

Thanks for the code and any help.

Annmarie