ECMAScript Explicit Resource Management & using Declarations

[DanielRosenwasser]

@rbuckton's proposal for Explicit Resource Management has reached stage 3 in TC39!

As such, it's time for TypeScript to look into its implementation. This proposal carries a few new features that TypeScript should have

• using declarations
• Symbol.dispose
• SuppressedError
• Iterator.prototype[Symbol.dispose]
• Possibly a new interface called Disposable (which I think we should consider calling DisposableLike)
• DisposableStack

We are in a slightly weird spot here since downlevel emit of using is possible, but will require a lib of esnext.

Given that the 5.1 timeframe will be shorter, it would be reasonable for our first stab at this feature to include only support for --target esnext.

Note that since Async Explicit Resource Management has been split off into its own proposal, I'm not suggesting we add it here.

[Kingwl]

Does this one accept PRs? Happy to work on this.

[rbuckton]

I have already started this effort, but thanks for the interest!

[rbuckton]

• Possibly a new interface called Disposable (which I think we should consider calling DisposableLike)

I'm hoping we shouldn't have the same kind of conflict in the future given that DisposableStack is the name of built-in class related to this feature. You generally don't perform other operations generically on a disposable like you do for iterators.

[MadProbe]

https://github.com/tc39/proposal-async-explicit-resource-management is stage 3 (see tc39/proposals) and it's planned to merge it back with sync version of proposal so could you update this issue and 5.1 iteration plan?