Size of a class instance at compile time

[Daniel Keep]

Frits van Bommel wrote:
> Frits van Bommel wrote:
> 
>> [1]: e.g. I haven't tested using anything with explicit align(N) 
>> declarations, not sure what happens there (would .alignof be adjusted?).
> 
> 
> Yep, definitely breaks there. But I did find a much more elegant 
> implementation that *does* work in that case (as well as in normal cases):
> 
> -----
> template InstanceSize(T)
> {
>     const InstanceSize =
>         T.tupleof[$-1].offsetof + T.tupleof[$-1].sizeof;
> }
> ------
> 
> _Way_ shorter, and always provides the correct answer under two simple 
> assumptions:
> 1) The last non-static member is also last in the layout
> 2) There's no padding at the end.
> 
> Assumption (1) is pretty likely to be broken if and when member 
> reordering is implemented, though.

Oh that's beautiful; I can't believe I forgot about offsetof!  Thanks 
very much for that: this should make the allocators a bit more efficient :)

	-- Daniel