On Tue, Sep 12, 2017 at 23:26 Gwendal Roué <[email protected]> wrote:
> > > Le 13 sept. 2017 à 04:05, Xiaodi Wu <[email protected]> a écrit : > > > > On Tue, Sep 12, 2017 at 2:30 PM, Gwendal Roué <[email protected]> > wrote: > > >> In none of those cases, the compiler emits any warning. It's thus > easy to forget or miss the problem, and uneasy to fix it (you'll need a > runtime failure to spot it, or a thorough code review). > > >> > > >> I hope you agree with this last sentence. This unbalance between the > easiness of the mistake and the easiness of the fix should ring a bell to > language designers. > > > > > > Suppose instead this were about a protocol named Fooable and a > requirement called foo() that has a default implementation. Everything you > just talked about would apply equally. Am I to understand that you are > opposed to default implementations in general? If so, then that’s got > nothing to do with synthesized Equatable conformance. If not, then you’ll > have to justify why. > > > > Sounds like a good argument, until one realises that if a protocol does > not provide a default implementations for a method, it may be because a > default implementations is impossible to provide (the most usual case), or > because it would be unwise to do so. > > > > And indeed, the topic currently discussed is not if we should remove or > not default implementations. Instead, the question is: is it wise or not to > provide an *implicit* default Equatable/Hashable/XXX implementation? > > > > Right, _that_ is the question. It was asked during review for the > proposal, and the agreed upon answer is _yes_. > > Wrong. This whole thread is about *explicit* synthetic behavior;. If an > agreed proposal has to be invalidated in the way, _so be it_. > > Gwendal Explicit (e.g., "AutoEquatable") and implicit synthetic behavior were both considered during the proposal which approved the implicit behavior. This question has been asked and answered.
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