On 18/12/15 16:46 , swift-evolution-requ...@swift.org wrote:
> Date: Fri, 18 Dec 2015 11:38:31 -0800
> From: Dave Abrahams <dabrah...@apple.com>
> Subject: Re: [swift-evolution] RFC: Proposed rewrite of Unmanaged<T>
> Message-ID: <e82aada9-f4a4-4e4e-98c3-6e9a3cec4...@apple.com>
>
>> > On Dec 17, 2015, at 6:23 PM, T.J. Usiyan <griotsp...@gmail.com> wrote:
>
>> > My main point of contention with `.release()` is that it has the *exact*
>> > same name as a method from the MRC strategy. Maybe this is a silly point,
>> > but this overlap could further complicate teaching how ARC works and in
>> > what ways it is based on MRC conventions.
>> > I am not of the opinion that ARC is fundamentally more difficult to
>> > understand than MRC, but I do believe that it takes a very particular kind
>> > of faith now that we don't get to manually write the retains and releases.
>> > This is completely worth it, in my opinion, but I want to avoid making it
>> > *more* confusing to explain what ARC doing at compile time.
> Well, unsafeRef.release() is equivalent to
>
> {
> let x = $0.object
> CFRelease($0) // if CFRelease() wasn't @unavailable
> return x
> }(unsafeRef)
>
> If you let the return value drop on the floor, it ends up being
> exactly equivalent to the method with the exact same name from the
> MRC strategy. So the correspondence is strong and shouldn’t be a
> problem. That’s just my opinion, though, and part of the reason
> we’re asking for feedback here is so people steeped in MRC like you
> can argue with me about that :-), so if you find this unconvincing
> please explain why.
OK, guess I qualify as "steeped" there - I still use MRC in all my
shipping apps, although I've tentatively used ARC in small fry like
build-time utilities. (Never got used to GC.)
Anyway, much of my code looks like one of these patterns:
// 1
NSDictionary* dict = [(id)CFCreateSomeCFDictionary() autorelease];
... use dict for some lines, done
// 2
NSArray* array = (NSArray*)CFGetSomeCFArray();
... use array for some lines, done
// 3
NSString* str = (NSString*)CFCreateSomeCFString();
... use str for some lines
[release str];
One thing about my not migrating to ARC is that I find the bridging cast
names opaque - can't memorize them! Same, sadly, was true for the
Umanaged<T> methods.
So I'd say, use `.release` or `.autorelease` if they'd be used in the
same place as above...
--
Rainer Brockerhoff <rai...@brockerhoff.net>
Belo Horizonte, Brazil
"In the affairs of others even fools are wise
In their own business even sages err."
http://brockerhoff.net/blog/
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