[swift-evolution] Philosophy of Swift
dabrahams at apple.com
Thu Jun 9 10:03:59 CDT 2016
on Wed Jun 08 2016, Paul Cantrell <paul-AT-bustoutsolutions.com> wrote:
>> On Jun 8, 2016, at 6:13 PM, Dave Abrahams via swift-evolution <swift-evolution at swift.org> wrote:
>> on Wed Jun 08 2016, Paul Cantrell <swift-evolution at swift.org> wrote:
>>> The interplay of the first two and the last two is what makes the
>>> language unique. For example, structs have a simple, high-level
>>> programmer model — “pass by value semantics” — but the compiler jumps
>>> through all those COW hoops to make them perform _most_ of the time as
>>> if they were C structs statically allocated and then passed by
>> I have no argument with most of what you wrote, but this part is just
>> inaccurate. Plain structs are never CoW'd, and the compiler doesn't
>> introduce CoW. The standard library implements CoW “manually” for
>> specific types like Array and String.
> So then only language/runtime magic is isUniquelyReferenced(), and all
> the other “hoops” are in the standard lib?
> I guess I just lump compiler and standard library together in my mind
> too carelessly!
It's the right user model most of the time. In this case, though, you
don't want to give people the impression that these things will be done
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