I think this is the kind of incremental refinement of the details of existing features that we can legitimately consider after May without setting a bad precedent. Would you be interested in turning these ideas into a strawman for, say, the July meeting?
Unless there's a problem with this approach I'm not noticing, I think it would be a welcome cleanup of a messy part of the language -- conditioned on an ES-next opt in of course. On Fri, May 13, 2011 at 2:05 AM, Andreas Rossberg <[email protected]>wrote: > On 13 May 2011 01:50, Mark S. Miller <[email protected]> wrote: > >> Assume that > >> > >> - we distinguish two variants of the eval function, strict and > >> non-strict -- let's call these values EVAL_s and EVAL_ns. > >> - initially (in global scope), the identifier `eval' is bound to > EVAL_ns. > >> - in a strict mode scope it will be considered rebound to EVAL_s > >> instead (unless it has already been shadowed by user code anyway). > >> > >> (In addition, at least in strict mode, the only calls to `eval' that > >> are considered _direct_ calls would be those where `eval' statically > >> refers to the initial binding or one of the implicit strict-mode > >> rebindings -- i.e., where it has not been shadowed by the user.) > > > > I think the core insight here is good, and had it been made in time, > could > > have led to a better semantics than what we adopted into ES5. I like the > > idea that ' "use strict";' effectively inserts a > > DeclarativeEnvironmentRecord binding 'eval' to EVAL_s, though I'd put > this > > record on the stack at the strict/non-strict boundary rather than just > above > > the global object. > > Yes, my previous description of "shadowing" `eval' at the point of > "use strict" was meant to describe just that. > > > Even better, since 'eval' cannot be rebound by ES5/strict, ES-next, or > SES > > code, and since "eval(str)" is effectively a special form anyway, why not > > remove the dynamic "and if 'eval' is bound to the original global eval > > function" condition from direct eval? Why not just treat "eval(str)" as a > > direct eval special form independent of what 'eval' is bound to in that > > scope? > > That's what I tried to suggest in the parenthesized paragraph above, > and it was the reason for my question to Allan. > > The difficulty in ES5 would be that scoping is not really static -- > not even in strict-mode code, which might still be surrounded by > non-script scopes shadowing `eval' dynamically (esp `with'). But for > Harmony it'd be nice. > > Thanks, > /Andreas > -- Cheers, --MarkM
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