[swift-evolution] [Draft] UnsafeRawPointer API

[L. Mihalkovic]

Regards
LM
(From mobile)

> On Jun 28, 2016, at 12:18 AM, Andrew Trick <atrick at apple.com> wrote:
> 
> 
>>> 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

I have to say, there are many situations when writing java code where i wished List<Int>.class existed.. instead I'd resort to xxx(List.class, Int.class) or to generic reflection on a abstract type token. 
So this DEFINITELY floats my boat!!!! As you say, it is the most accurate depiction of what truly happens.
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