On Sunday, 14 December 2014 at 16:05:13 UTC, Dan Olson wrote:
"Marc "Schütz\"" <schue...@gmx.net> writes:
On Saturday, 13 December 2014 at 21:20:43 UTC, Andrey
Derzhavin wrote:
import std.stdio;
class ObjectAType {
bool ok;
this() {ok = true;}
}
void main()
{
auto a = new ObjectAType;
assert(a.ok);
destroy(a);
assert(!a.ok); // a has been destroyed.
}
This method of detection of collected objects is what I
needed.
Thanks to everybody for your advise.
Be careful - the memory could still have been reused. For
example:
assert(a.ok);
destroy(a);
// ... lots of code, maybe multi-threaded ...
assert(!a.ok); // can fail
If between `destroy()` and the second `assert()`, the memory
of the
object is collected, a new object (of the same or different
type) can
have been placed there. You will then read an arbitrary piece
of data
from that new object, which may or may not evaluate to `true`.
In this case the object cannot be collected by gc because there
is still
a good reference to it (variable 'a'). I agree if delete was
used
instead of destroy that is would be unsafe.
--
dano
Right, but I see it only as a simplified example. In a real
program, that reference will most likely be a member of object
whose destructor is being run.
