Re: CFBridging... Functions in Corebase

[Stefan Bidigaray]

So CFBridgingRelease() essentially calls -autorelease, and CFBridgingRetain() -retain? I kind of get why, but only after thinking about it for an hour.

On Tue, Aug 22, 2017 at 12:56 PM, Fred Kiefer <address@hidden> wrote:

> Am 22.08.2017 um 17:15 schrieb Stefan Bidigaray <address@hidden>:
>
> Hi everyone,
> This message is mostly for Daniel, but anyone with some experience using these functions should not hesitate to add their thoughts.
>
> Daniel, I just noticed your pull request on github last night. I'm good with most of it, my only concern is the bridging functions. I made a comment last night, but later discovered I misunderstood their purpose. I'd like to get your pull request merged, and want do discuss it before we move forward.
>
> My understanding of the documentation for CFBridgingRelease and CFBridgingRetain is that they are essentially no-ops, unless ARC is in effect. And even when ARC is being used they do not do anything other than tell the compiler that the object is now controlled by ARC. With that in mind, these two "functions" should do nothing other than cast the CF object as an ARC aware object, and nothing at all if ARC is not implemented. Does this sound reasonable? Another part of this conversation is where do these functions belong. According to the Apple documentation, they are part of Foundation, so should they not be in Base, instead?
>
> As for CFAutorelease, I think this is the function where objc_autoreleaseReturnValue() needs to be used. The documentation for this function is nonexistent, so I'm just guessing at what it really does.
>
> Any thoughts? Anyone?

Stefan,

I think you are mostly correct. Apple has this stuff in Foundation, but we don’t build base on top of CoreFoundation, so we need to have it the other way around. In ARC-mode these two functions should call the compiler primitives David pointed to. Where you are incorrect is the non-ARC-mode. There Apple seems to implement these functions as retain and (auto-)release. Don’t ask me why, your interpretations makes more sense to me.

Fred



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