Jim,

I may be reading this incorrectly, but it doesn't sound right to me.

I see "A" as having to be in RAM as well as "B" when "B" is a subclass of "A" (which I assume 'derived from' means).

I don't see how the size of "A" is in any way dependent on the size of "B" or vise-versa when "B" is a subclass of "A".

I suspect I'm mis-reading something here.

regards,

Jim N

>Calvin,
>
>Excuse me for jumping in here, but I happened to come across this thread and got interested.
>
>I would add to Vlad's response that when A is derived from B, A and B are both in memory, but A's contents are much smaller then B's because A contains a reference to B and instructions on what changes were made in B to produce A.
>
>When you instantiate A and test for memmory used, the derive A from B, the amount of memory used is much less than double. Clearly then A is referencing B for a lot of the information used to create A.
>
>What that tells me is that if I create B then derive one instance from it, I have actually used up more memory than if I just used B instead of deriving A from it and using A. But if I derive A, C, D, E, and F., the memory savings are considerable over using B five times.
>
>regards,