On 13.09.2017 17:13, Haravikk via swift-evolution wrote:
Well, certainly, synthesized default implementations differ from non-synthesized
ones in key respects. However, they do not differ in terms of the user experience
of conforming to the protocol and having to override the default.
Except that that's not true at all, is it?
Synthesised default implementations go much further in how they attempt (and
potentially fail) to implement those defaults, and in the specific case of
Equatable/Hashable they are fully implementing a protocol without a single property
of method being raised as a requirement; they are utterly different at a fundamental
level, no amount of mental contortion changes that fact.
FWIW Fully agree with Haravikk. Just want to add my 2 cents. We hear an opinion that
protocol with auto-synthesization of requirements should be treated as a normal
protocol with deault implenentation. So, this is just a variant of default
implementation.
Actually I can agree with this. *BUT.* Such a *well-declared* protocol, which uses
macros/reflection/other to access *type's fields* to implement the default methods
IMO should also be explicitly conformed with 'deriving'-like keyword to be able to
synthesize methods. For example, as first thoughts, such protocol should be marked
with some kind of @synthesizable directive and probably have some helpers in this
case from compiler to implement synthesizable defaults. Yes, one probably can
implement protocol which uses macros/reflection without @synthesizable directive for
protocol, but this should be considered as not-well-formed protocol.
Vladimir.
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