Wait, if variadic calls aren't supported, how is it that NSLog() can be called?

> On Oct 18, 2014, at 18:22 , Roland King <r...@rols.org> wrote:
> 
> 
>> On 19 Oct 2014, at 9:03 am, Rick Mann <rm...@latencyzero.com> wrote:
>> 
>> 
>>> On Oct 18, 2014, at 16:40 , Roland King <r...@rols.org> wrote:
>>> 
>>> 
>>>> On 19 Oct 2014, at 5:23 am, Jean-Daniel Dupas <mail...@xenonium.com> 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.


-- 
Rick Mann
rm...@latencyzero.com



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