On Wednesday, 26 July 2017 at 22:33:23 UTC, Steven Schveighoffer
wrote:
On 7/26/17 2:33 PM, Moritz Maxeiner wrote:
On Wednesday, 26 July 2017 at 17:38:28 UTC, Dgame wrote:
I don't get it. The GC collects the objects which aren't in
use anymore. The order in which this is currently happening
is not specified. So, how are the destructors supposed to be
called in the right order? Manually? ARC?
After the split:
Destructors are only for deterministic end of object lifetime,
so yes, they are to be called by any scheme (such as manual
management via destroy and reference counting - which is
likely also implemented as calling destroy) that is
deterministic.
Finalizers are for nondeterministic schemes such as the GC.
The GC *never* calls destructors directly, only finalizers.
A finalizer might manually call a destructor, but a destructor
may never call a finalizer.
Actually, it's the opposite.
It's a matter of definition and this is the behaviour I would
define, because
A finalizer can never call anything on its members because it
doesn't know if it's being destroyed by the GC.
This falsely assumes that all members point into the GC pool. A
finalizer may freely work on non-pointer members and pointer
members that target objects outside the GC pool which the
programmer knows to be valid at finalization (e.g. they are
manually managed).
Whether or not it makes sense for the finalizer to call the
destructor is something the programmer has to decide on a per use
case basis.
The destructor is ensured that the entire structure is intact,
so it can do whatever it wants.
The point is that I saw (and see) no reason for a destructor to
ever call a finalizer.
