[swift-evolution] [Pitch] UnsafePointer.advanced(to:)

[Hooman Mehr]

> On Jun 6, 2017, at 12:56 PM, Dave Abrahams via swift-evolution <swift-evolution at swift.org> wrote:
> 
> 
> on Tue Jun 06 2017, Brent Royal-Gordon <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> 
>>> On Jun 6, 2017, at 9:06 AM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
>>> 
>>> Why would this be an extension on UnsafePointer and not KeyPath?
>> 
>> 1. I can't come up with a name as good as `advanced(to:)` that would
>> be attached to the key path. I use `advance(_:)` in the other two
>> reasons below, but I don't think it's nearly as clear about what it's
>> doing to the pointer.
>> 
>> 
>> 2. Passing the pointer as the parameter would encourage use of `&`, which would be invalid.
>> 
>> 	(\CGRect.origin.y).advance(&myRect)		// Pointer might be to a temporary
>> 	(&myRect).advanced(to: \.origin.y) // Rejected during compilation because & is not allowed
>> there
>> 
>> 3. Passing the key path as a parameter improves the code's appearance when you specify the key path
>> in the expression.
>> 
>> 	myRectPtr.advanced(to: \.origin.y)
>> 	(\CGRect.origin.y).advance(myRectPtr) // Requires explicit type name and extra parentheses
> 
> IIUC this has nothing to do with "advancing", though.  Maybe "applying"
> or even "map" would be a better name?

How about `offset`?


> -- 
> -Dave
> 
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