Re: GC pros and cons
Re: GC pros and cons
- Subject: Re: GC pros and cons
- From: Peter Duniho <email@hidden>
- Date: Sun, 28 Jun 2009 16:33:53 -0700
On Jun 28, 2009, at 4:12 PM, Michael Ash wrote:
On Sun, Jun 28, 2009 at 1:17 PM, Quincey
Morris<email@hidden> wrote:
I think the answer is in Bill's "entirely", above.
Without CFMakeCollectable, the final CFRetain will trigger the
calling of (a
hypothetical) CFDispose with the traditional timing (i.e.
immediately, we
assume, somewhat at our peril).
[...] Thus GC-unaware code gets the behavior at CFRelease time that
it expects
(somewhat at its peril), whether or not it is running in a GC-enabled
environment.
"If the object is in the garbage collected zone, the last CFRelease()
does not immediately free the object, it simply makes it eligible to
be reclaimed by the collector when it is discovered to be
unreachable—that is, once all strong references to it are gone. Thus
as long as the object is still referenced from an object-type instance
variable (that hasn't been marked as__weak), a register, the stack, or
a global variable, it will not be collected."
From the Garbage Collection Programming guide.
Your way sounds sensible, but according to the docs that's not how
it is.
Maybe I'm misreading one, or the other, or both of your messages, but
it seems to me that what Quincy wrote is in agreement with what you
quoted.
In particular, my (admittedly inexperienced) understanding is that an
object winds up "in the garbage collected zone" when code calls
CFMakeCollectable. Conversely, "GC-unaware code" would not, I would
think, call CFMakeCollectable (that seems like a very "GC-aware" thing
to do, right?).
I suppose in a scenario where some code is using an object allocated
by some other code, where that other code has called
CFMakeCollectable, but the first code is "GC-unaware", that would be
an exception to the statements made. But it doesn't seem like an
important exception to me, because that first code shouldn't be
assuming ownership or control over the object anyway (i.e. obviously
it got the object from somewhere else, and it has no reason to believe
that it holds the last retain on the object, even if that first code
doesn't know anything about garbage-collection).
If I've somehow misconstrued what either of you wrote, I apologize.
But as things stand now, I'm not convinced you're in contradiction
with each other.
Pete_______________________________________________
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