[swift-evolution] [Pitch] Make the formal type of 'self' consistent in class methods
Andrew Trick
atrick at apple.com
Thu Jun 23 16:02:51 CDT 2016
> On Jun 23, 2016, at 1:48 PM, Slava Pestov <spestov at apple.com> wrote:
>
>
>> On Jun 23, 2016, at 1:46 PM, Andrew Trick <atrick at apple.com <mailto:atrick at apple.com>> wrote:
>>
>>
>>> On Jun 23, 2016, at 12:53 PM, Slava Pestov via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>
>>> The proposal is to change the type of self to always be Self, which can be thought of as a special generic type parameter bound to the dynamic type of the instance.
>>
>> We’re currently specializing functions that take `self` as an argument. I don’t think that will be possible after your proposed change.
>>
>> - Andy
>
> I’m not sure what that means. Do you currently punt on certain optimizations if a method returns ‘Self’?
>
> It should be possible to keep the reified type information around, by passing in a metatype or something for example. Can you give a concrete code snippet demonstrating the optimization and how this change would inhibit it?
We bail out of generic specialization, inlining, and function signature specialization when a type substitution contains dynamic self. (hasDynamicSelfTypes). So, yes we currently almost entirely punt on optimization for methods that return Self.
I don’t have an interesting case to point out. You can look into any trivial example:
func foo<T>(_: T) {}
func method() {
foo(self)
}
-Andy
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20160623/46174f3b/attachment.html>
More information about the swift-evolution
mailing list