On 12/4/2014 3:04 PM, deadalnix wrote:
So as mentioned, there are various problem with this DIP :
- rvalue are defined as having a scope that goes to the end of the statement.
That mean they can never be assigned to anything as per spec.
I don't believe this is correct. Rvalues can be assigned, just like:
__gshared int x;
{ int i; x = i; }
i's scope ends at the } but it can still be assigned to x.
- It add more special casing with & (as if it wasn't enough of a mess with
@property, optional () and the fact the function aren't first class). For
instance *e has infinite lifetime when &(*e) is lifetime(e).
That's right. I know you're worried about that, but I still don't see it as an
actual problem. (The optimizer makes use of this special case all the time.)
Also, considering *e has infinite lifetime, (but not e[i] ???)
e[i] should be same as *e, unless e is a literal or tuple.
what is the point of scope at all ? If all indirection goes to infinite
lifetime (ie GC) then
lifetime only apply to local variable and it should not be able to escape these,
scope or not.
I originally had scope only apply to ref, but that made having scoped classes
impossible.
During discussion, I proposed to differentiate lifetime calculation between
lvalues and rvalues (which are inherently different beasts with different
lifetime) and carry (or not) the scope flag with each expression.
I'm not sure how that would be different from the DIP as it stands now.
