> Subject: Re: using autorelease in apple's CF
> From: thera...@sucs.org
> Date: Wed, 13 May 2015 09:51:47 +0100
> CC: gnustep-dev@gnu.org
> To: alexey.pereva...@hotmail.com
>
> On 13 May 2015, at 09:39, Alexey Perevalov <alexey.pereva...@hotmail.com>
> wrote:
> >
> > If I truly understand, to place object into autorelease pool need to send
> > autorelease message [object autorelease], it will release ownership from
> > client code,
> > in details, it just send addObject of AutoreleasePool instance, it puts
> > object into pool.
> >
> > In my implementation, for example of CFString,
> > CFStringRef CFStringCreateWithCString(CFAllocatorRef allocator, const char
> > *cString, CFStringEncoding encoding){
> > return ToCFString([[NSString allocWithZone:NULL] initWithCString:cString
> > encoding:convertCFEncodingToNSEncoding(encoding)]);
> > }
> >
> > Just NSString is created, and initWithCString is not calling autorelase,
> > but stringWithCString is calling it.
> > So if in CFStringCreateWithCString just send autorelease for newly created
> > object, no need to warry about releasing it in client code,
> > in case of client is ARC enabled.
>
> I don’t think I understand the last bit. Autoreleasing something means ‘I
> have a temporary reference to this, which I intend to pass up the stack, and
> it should be deleted at some point in the future’. You trade not having to
> release it in the calling code for having to retain it in the calling code if
> it does want to retain a reference to the object.
>
> Autoreleasing is also slower than releasing because it requires adding the
> object to the pool and then popping it later. It’s also not great for memory
> consumption, because the object will be kept alive by the reference owned by
> the autorelease pool, right until the point at which it is deleted.
>
> This is why, in ARC mode, the compiler has the option of promoting a returned
> autoreleased object to a retained object and then explicitly releasing it.
>
> The main reason to use autoreleased references is if you expect to have a lot
> of assignments of that reference to temporaries as the reference is
> propagated up the stack. These won’t need retain count manipulations.
>
> In pre-ARC Objective-C, autorelease was also a good way of returning
> temporary objects, as the caller didn’t need to free them. With ARC, the
> compiler will do the same thing more efficiently (and reduce overall memory
> usage).
>
> What problem are you actually trying to solve?
Just check GCDAsyncSocket (mentioned above) with CFStreamCreatePairWithSocket
implemented through NSIn/Output streams ;)
>
> David
>
> -- Sent from my brain
>
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