On Fri, 13 Jul 2018 at 18:00, Andrei Alexandrescu via Digitalmars-d <digitalmars-d@puremagic.com> wrote: > > On 7/13/18 5:49 PM, rikki cattermole wrote: > > On 14/07/2018 9:28 AM, Manu wrote: > >> I've already contributed other points to this DIP in the way you > >> describe. > >> This one however is very strange, and I'm surprised you can find the > >> hand-wavy introduction of a new attribute without any sense of where > >> it's going to be okay. Or maybe, I'm surprised I'm the only one that > >> finds problem with that. > > > > You are very much not alone. > > > > I didn't articulate it very clearly, but I am super not happy with such > > a new attribute. > > It's a very simple process - @implicit is not invented as much as a given. > > We need to distinguish a constructor from other constructors. > > The constructor supports attributes. > > Attributes are a mechanism for distinguishing declarations from other > declarations. > > Ergo, an attribute is the mechanism of choice. > > Done deal. > > ===== > > If we don't like the use of an attribute, it means we somehow failed in > defining attributes in the first place. (I don't think we did; > attributes as defined in D are brilliant and currently underused.) It's > poor language design to define a mechanism for doing a category of Xs > and then explicitly avoiding it exactly when the opportunity of doing X > arises. > > From that vantage point, the choice of an attribute to identify > implicit copy construction is unassailably obvious, and elucubrated > syntax inventions such as "@this", "this(ref this x)" are chucklesomely > profligate and ridiculously baroque.
But you surely recognise that D has a lot of intrinsic attributes already, and that's a lot of mental (and visual) baggage to carry around. If we add a new intrinsic attribute, I would want to be sure it's widely useful, because every D user will need to learn about and understand it. It's much easier to learn, and more useful knowledge to have, if it has a broad meaning which solves a general class of problem, than just a marker that you need to remember you have to type in one specific niche location.
