> Given <script type="harmony"> as an opt-in, I'm puzzled about how it would
> work anyway. Since it is per script, not per frame, presumably
>
> <script type="harmony">"use strict"; var e1 = eval;</script>
> <script>"use strict"; var e2 = eval;</script>
> <script ...>"use strict"; e1 === e2 /*results in true*/ </script>
That's not quite right, at least according to the simple modules design. But
it's my fault for not spelling it out clearly enough in the strawman. In
particular:
- Harmony scripts would not have the legacy global object as a record in their
scope chain
- Harmony eval retains the same value and behavior as ES5-strict eval, i.e., it
evaluates its code as legacy code, not as Harmony code.
Both of these are open to discussion, of course, but I offer them at least as
counter-evidence to your implication that there's no answer to the versioning
question other than eliminating modes.
The invariants of Harmony do *not* rely on not interacting with legacy code.
You still get lexical scope, and ES5-strict eval is sufficient for that
purpose. (When you run eval, of course, you're running code in a language that
doesn't have full lexical scope.)
> In other words, that both harmony and non harmony code on the same page have
> the same binding for the global "eval" function. In that case, what does the
> following code do:
>
> e2(' "use strict"; var module = 8;');
>
> This is currently legal es5/strict code. As suggested by the modules
> strawman, it is not legal harmony code.
It's perfectly legal. It's an indirect eval, regardless of whether it's being
called from ES5-strict or Harmony.
> es5/strict and harmony share a heap.
Yep, and that's fine.
> I do not see a good answer.
As you say, that's why it's worth discussing.
Dave
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