> On Apr 5, 2016, at 3:02 PM, Erica Sadun <er...@ericasadun.com> wrote:
>
> As the discussion seems to be quieting down, I've tried to summarize the
> on-list discussion and distill it into a preliminary proposal draft. Please
> let me know if this covers what you think it should or if I've entirely
> missed the mark. (It wouldn't be the first time.)
>
> Regards, -- Erica
>
> Adding a #Self literal to Swift
>
> • Proposal: SE-XXXX
> • Author(s): Erica Sadun
> • Status: TBD
> • Review manager: TBD
> Introduction
>
> This proposal introduces #Self, a new literal that expands to
> self.dynamicType.
>
> This proposal was discussed on the Swift Evolution list in the [Pitch] Adding
> a Self type name shortcut for static member access thread.
>
> Motivation
>
> It is common in Swift to reference an instance's type, whether for accessing
> a static member or passing a type for an unsafe bitcast, among other uses. At
> this time, you can either fully specify a type by name or use
> self.dynamicType to access an instance's dynamic runtime type as a value.
>
> struct MyStruct {
> static func staticMethod() { ... }
> func instanceMethod() {
> MyStruct.staticMethod()
> self.dynamicType.staticMethod()
> }
> }
>
> • As type names grow large, readability suffers, for example
> MyExtremelyLargeTypeName.staticMember
> • Code using hardwired type names is less portable than code that
> automatically knows its type.
> • Renaming a type means updating any TypeName references in code.
> • Using self.dynamicType fights against Swift's goals of concision and
> clarity; it is both noisy and esoteric.
> • self.dynamicType.classMember and TypeName.classMember may not be
> synonyms in class types with non-final members.
> • Joe Groff points out, Self inside a class scope already means "the
> dynamic class of 'self'", not "the type this declaration statically appears
> within...Swift ought to allow developers to utter Self in the bodies of class
> methods. It would be consistent to extend that courtesy to value types, where
> dynamic Self always matches the static type, from that principle"
> Detail Design
>
> In this proposal, #Self expands to the dynamic type of self and only the
> dynamic type of self. Joe Groff writes, "I don't think it's all that onerous
> to have to write ClassName.foo if that's really what you specifically mean."
What you're describing should be spelled `Self`, IMO. I think Tim intended
`#Self` to mean the *static* type the code is declared inside (which is the
same as Self unless you're in a class).
-Joe
> Alternatives Considered
>
> Not at this time
>
> Acknowlegements
>
> Thanks Sean Heber, Kevin Ballard, Joe Groff, Timothy Wood, Brent
> Royal-Gordon, Andrey Tarantsov, Austin Zheng
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