move object from heap to stack

[monarch_dodra]

On Thursday, 20 September 2012 at 08:10:36 UTC, Namespace wrote:
> You're right.
> This is my next try: http://dpaste.dzfl.pl/02b32d33
> Do you have anything else to say? :)

I think it looks good, but I'm unsure about "move", or allowing 
pass by value:

Classes can't be memcopied the way structs can: Class may have 
default constructors, or copy constructors, which would be 
totally ignored by a memcopy. For example, if your class had a 
"RefCounted" member, its postblit would never be called, and it 
would then be "over destroyed":

--------
class A
{
     RefCounted!int rf;
     this()
     {
         rf.RefCounted.ensureInitialized();
         rf = 5;
     }
}

void main()
{
     A a = new A();
     OnStack!A osa = OnStack!A.move(a);
}
--------
core.exception.InvalidMemoryOperationError
--------
Here, osa makes a binary copy of the RefCounted, so the count 
stays at 1.
Then, when osa is destroyed, it deletes the RefCounted's store.
However, when a is destroyed, it still has a pointer to the 
(deleted) store, creating the Error...

I think "move" has to go, because classes are just not moveable. 
pass by value can stay, if and only if, T gives a copy 
constructor. Or NO constructors (in which case a memcopy should 
be the same as a default copy).