Re: How does the Swift Darwin module work?
Re: How does the Swift Darwin module work?
- Subject: Re: How does the Swift Darwin module work?
- From: Roland King <email@hidden>
- Date: Sun, 19 Oct 2014 09:22:51 +0800
> On 19 Oct 2014, at 9:03 am, Rick Mann <email@hidden> wrote:
>
>
>> On Oct 18, 2014, at 16:40 , Roland King <email@hidden> wrote:
>>
>>
>>> On 19 Oct 2014, at 5:23 am, Jean-Daniel Dupas <email@hidden> wrote:
>>>
>>> AFAIK, variadic C functions are not (yet) callable from swift code.
>>>
>>>
>>
>> They aren’t - I didn’t remember fnctl() was varidadic. I shall quote an Apple engineer then ..
>>
>> "This is not possible in Swift. C variadics are inherently unsafe, and not compatible with Swift variadics. You're encouraged to provide alternate versions of your collection-y variadics that take an array. Your format-y variadics (like this one?) can use Swift's String's variadic initializers ahead of time."
>>
>> So you get to go wrap fcntl() in something else it seems.
>
> So, how would I do that, exactly? I suppose I have to pass Objective-C collection types to a method (which could be a straight C function) from a Swift call? That is, can a Swift variadic call translate into a C function call that accepts Obj-C collections?
Write a simple c wrapper around the thing you’re trying to do and that bridges across to swift. You could probably try to write something really generic which wraps fcntl() using an UnsafeMutablePtr<UInt8> as a final argument and then massaging stuff in Swift to poke it over and back, but that really would be a horror. You’re probably better off just shimming the actual operations you really actually need into a set of specialized c calls, each one should take 2-3 lines of code only for that.
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