Seems to me that we can find similar information just from walking over a
class's fields to build an ownership graph, and cause warnings/errors when you
find a strong cycle.
How do you deal with type erasure?
> protocol Foo {}
> class A {
> var foo: Foo
> }
> class B: Foo {
> var a: A
> }
> // A and B can have a cycle through the Foo protocol
Also, how do you encode that your example's "addCallback" closure parameter
can't have a strong reference to `self`?
Félix
> Le 29 juil. 2016 à 18:42:11, Andrew Bennett via swift-evolution
> <[email protected]> a écrit :
>
> I'd like an opt-in way to verify and prevent unintentional strong references
> in Swift.
>
> This can be used to verify ownership structures, and ultimately avoid retain
> cycles.
>
> Read a draft proposal here:
> https://github.com/therealbnut/swift-evolution/blob/therealbnut-explicit-ownership/proposals/NNNN-explicit-ownership-type-attribute.md
>
> <https://github.com/therealbnut/swift-evolution/blob/therealbnut-explicit-ownership/proposals/NNNN-explicit-ownership-type-attribute.md>
>
> TL;DR:
>
> If you have any questions please read the proposal before asking here.
>
> It's an opt-in attribute that defines a whitelist of types something can own.
> For example:
>
> @owns(TypeA, TypeB) struct TypeC { ... }
>
> I wrote this a few months ago, but we weren't accepting additive proposals.
> Now we're explicitly looking for something like this:
>
> Memory ownership model: Adding an (opt-in) Cyclone/Rust inspired memory
> ownership model to Swift is highly desired by systems programmers and folks
> who want predictable and deterministic performance (for example, in real time
> audio processing code). More pertinent to the goals of Swift 4, this feature
> is important because it fundamentally shapes the ABI. It informs code
> generation for “inout", how low-level “addressors” work in the ABI, impacts
> the Swift runtime, and will have a significant impact on the type system and
> name mangling.
>
> - Chris
> <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160725/025676.html>
>
> ----
>
> Here's a link to the version of the proposal
> <https://github.com/therealbnut/swift-evolution/commit/6ab167825d802c7826804e1957eb515d3009743a>
> when I sent this email.
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