Get class size of object

[JS]

On Sunday, 11 August 2013 at 17:19:21 UTC, Adam D. Ruppe wrote:
> On Sunday, 11 August 2013 at 17:03:04 UTC, JS wrote:
>> For those that care, here is a snippet of what I am doing.
>
> What are you actually going to use the number for? If you are 
> going to write your own New function, you'll need the init 
> anyway, so you aren't really paying more to get the size from 
> it either.

What's the difference between init.length and classInstanceSize? 
The class instance size must be known at compile time and I don't 
see why there will be a difference and what little testing I have 
done shows no difference.