Clean Context

[martinheidegger]

Having complex systems with various variables could result in leaking unintended values to subsystems. It might be reasonable to have something like AsyncContext.sandbox(() => {... }) which reset's all the state, preventing parents to interfere.

const asyncVar = new AsyncContext.Variable();

// Sets the current value to 'top', and executes the `main` function.
asyncVar.run("top", main);

function main() {
    AsyncContext.sandbox(() => {
      console.log(asyncVar.get()); // => undefined
    });
}

[Qard]

Just for context, in Node.js this is store.exit(() => {}).

[iliasbhal]

the sandbox() feature can be implemented by creating a snapshot from the global scope. no?

const asyncVar = new AsyncContext.Variable();
const sandbox = new AsyncContext.Snapshot()

// Sets the current value to 'top', and executes the `main` function.
asyncVar.run("top", main);

function main() {
    sandbox.run(() => {
      console.log(asyncVar.get()); // => undefined
    });
}

[andreubotella]

the sandbox() feature can be implemented by creating a snapshot from the global scope. no?

Yes, but CommonJS libraries in Node.js would not have access to the global scope.

In the web integration, we are proposing that some event listeners (e.g. for a user-caused click event) would have a clean context. We are also proposing that ES modules would be run with a clean context, because each module is only ever run once, and @nicolo-ribaudo argues that they shouldn't be able to observe what caused the module to be imported. Given that, each ES module would have access to the clean context, and there might be other ways for CommonJS modules and regular <script>s to get it.