On Wed, 10 Apr 2013 11:08:22 +0100, Regan Heath <[email protected]>
wrote:
On Wed, 10 Apr 2013 10:48:30 +0100, Henning Pohl
<[email protected]> wrote:
On Tuesday, 9 April 2013 at 20:46:12 UTC, Steven Schveighoffer wrote:
No. You are not allowed to access any GC-managed resources inside a
destructor.
Okay, I finally found it: http://dlang.org/class.html#destructors. But
it's not listed here: http://dlang.org/garbage.html.
And it won't be null, because that would be extremely costly.
Consider if 300 objects had a pointer to a block of memory. Now those
300 objects all go away. By your expectation, if the targeted block
of memory was collected, the GC would have to spend time going through
all those 300 pointers, setting them to null. When they are about to
all be destroyed. 99.99% of the time, that would be wasted, as those
300 objects may not even have destructors that care.
I thought about the case when the user sets the reference to null
before the destructor was even called.
A destructor is ONLY for destroying non-GC managed resources, nothing
else. Like an OS file handle for instance.
Imagine this case:
...
Any instance of B always needs to be destructed _before_ the A it's
connected to. How do you express this in D?
Actually I got my example a bit wrong. You can at least destroy the a
library handle in Dispose(true/false). But, you cannot call a.Dispose()
from b's Dispose(false) and from what you're saying, you cannot free the
library b handle either.
R
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