Understanding live exports rules

[tmpfs]

Just a general discussion to help me understand the rules for live exports. So far I think that the following are live exports:

• Late assignment to an exported variable
• Re-export from an imported module
• Exported function expression
• Exported class declaration

Are there other cases where I should transform as a live export?

Regarding the exported function expression it appears that the Object.defineProperty() and $h‍_live.fn($c‍_fn); are hoisted to the top; currently my transform is not doing this (input & output) - I assume it is required?. See the output of test case 6 for the output with hoisting.

Also I am a bit confused by test case 7. Why is it calling $h‍_live.C(C); when the exported variable is count I would expect it to operate on the exported variable not the class definition. Any pointers much appreciated!

[tmpfs]

Apologies, I mis-read the output program for test case 7 I see now that both the variable count and the class C are treated as live exports.

I didn't realize that exported classes can be re-assigned, this was unexpected for me:

export class C {}

C = function foo() {
  console.log('baz');
}

C()

[erights]

Test case 7 is

export let count = 0;
export class C {} if (C) { count += 1; }

I see why count is a live binding --- it is assigned to.
But why is C considered a live binding? It is not assigned to.

[tmpfs]

@erights, it seems that exported classes can be re-assigned (which I didn't know) however you are right that in Test Case 7 there is no assignment and it would be safe to skip the live export IMO.

This would be a case where we would need a live export I think (C.mjs):

export class C {};

C = function() {
  console.log('baz')
}

Then import it and the function assignment which overrides the class is used:

import {C} from './C.mjs'
C()