> On Oct 27, 2017, at 9:27 AM, Mike Kluev via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> if it wasn't already discussed here is the preliminary proposal, if it was
> then my +1 to the feature.
>
> i propose we have an explicit apparatus to denote classes having stack
> storage.
>
> stack class StackObject { // guaranteed to be on stack
> }
>
> class NonStackObject { // is not guaranteed to be on stack, can be on heap as
> well
> }
>
> this is for performance reasons. sometimes what we need is “structs with
> deinit” and as this is not going to happen the next best thing could be
> “lightweight” classes. this shall be self obvious, here are few examples:
Move-only struct types will be able to provide deinit. See the ownership
manifesto.
John.
>
> stack class StackObject {
> var variable = 0
>
> func foo() {
> print(“i am ok to live on stack”)
> }
> }
>
> stack class BadObject {
> var variable = 0
>
> func foo() {
> DispatchQueue.main.async { // error: can’t be a stack class
> self.variable = 1
> }
> }
> }
>
> class NonStackObject {
> …
> }
>
> foo() {
> let stackObject = StackObject()
>
> DispatchQueue.main.async {
> stackObject.foo() // error: can’t use a stack object in this context
> }
> }
>
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