[swift-evolution] [Draft] UnsafeRawPointer API

[Andrew Trick]

> On Jun 27, 2016, at 1:52 PM, L. Mihalkovic <laurent.mihalkovic at gmail.com> wrote:
> 
>  think you mean T.Type, not T.self, because this looks like a declaration.
>> 
>> To evaluate, you have to look at the use-site:
>> 
>>   let p = UnsafePointer(r, to: Int.self)
>> 
>> I don't find “to” to be descriptive enough.  Maybe
> 
> toType
> 
>> 
>>   let p = UnsafePointer(r, pointee: Int.self)
> 
> I find pointee a total aberation :)
> 
>> 
>> is better.  But I hate that the language doesn't give us a way to say
>> “don't deduce generic parameters here.”  This is the only syntax that
>> feels right, IMO:
>> 
>>   let p = UnsafePointer<Int>(r)
>> 
>>> Option (3) UnsafeRawPointer.unsafeCast<T>(to: T.Type) ->
>>> UnsafePointer<T>
>> 
>>   r.unsafeCast(to: Int.self)
>> 
>> I don't see adding “unsafe” to the name of the operation as adding
>> anything.  It isn't any more unsafe than other UnsafeRawPointer
>> operations.  
> 
> It is unsafe in the sense that there are no guarantees that it is a sensible thing to do. I guess that means it is more 'noguaranteeexplicitorimpliedapplied' in the sense that it will like mechanically work, even if it produce an aberation as a result
> 
>> Also, it reads like we're casting the raw pointer to an
>> Int, rather than to an UnsafePointer<Int>.
> 
> Really good one... But then instead of 'to' or 'pointee', something along the lines of 'wrappedType', which lookes a little less balerina-ish than pointee.....
> 


Any gripes about this syntax?

let ptrB = UnsafeRawPointer(ptrA).cast(to: UnsafePointer<B>.Type)

It meets the goal of being perfectly explicit. We can add convenience APIs for certain cases later.

-Andy
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