On 2011-04-27 15:15, Steven Schveighoffer wrote:
On Wed, 27 Apr 2011 07:42:22 -0400, Mariusz Gliwiński
<alienballa...@gmail.com> wrote:
Hello,
I'm next person, which isn't necessarily happy about delete operator
deprecation.
Because constructors / destructors are frequently used not only for
application controlled memory management, how would You implement
something like following code without delete operator?
You can use clear to call the destructor of a class, and then GC.free
(if you wish) to free the memory. The recommendation is to only use
clear, and then let the GC clean up the memory at its leisure.
<code>
void main(string[] args) {
auto res = new Resource();
auto s1 = new FirstSystem(res);
delete s1;
auto s2 = new SecondSystem(res);
}
class FirstSystem {
this(Resource res) {
res.referenced = true;
}
~this() {
res.referenced=false;
}
}
class SecondSystem {
this(Resource res) {
assert(!res.referenced);
}
}
</code>
Note there is a serious flaw in your destructor. Destructors cannot
access GC managed memory because if the destructor is called inside the
GC, the GC managed memory being referenced may have already been destroyed.
Next questions would be:
* Are you going to drop destructor as well, or maybe destructor is going
to be confusing feature with non-deterministic behaviour? (How would i
know when heap allocated Socket will be destructed -> when connection
will be closed -> if my system gonna be DoS'ed?)
If the Socket closes its resources in the finalizer, then use clear().
If the destructor does not close the resource (as could be the case if
the resource is GC managed), you must implement a deterministic
destructor member (with a different name, like close()) that you can
call separately from the finalizer. There is no formal design for this,
I really think there should be.
You mean like "dispose" in Tango. That's called when "delete" or "scope"
is used.
* Are you going to stop supporting object oriented programming? (Well,
if *deterministic* resource managing can be only inside function, and
not object boundaries, that's my conclusion).
I assume this is rhetorical.
-Steve
--
/Jacob Carlborg
