FWIW: I've written down my understanding of the differences
between LexicalEnvironment and VariableEnvironment in ECMA-262:
http://www.2ality.com/2011/04/ecmascript-5-spec-lexicalenvironment.html
Thanks, another surprising detail. The standard disallows
FunctionDeclaration as statement, acknowledges that
implementations don't follow suit, and recommends that
they should [12, Note].
Perhaps you should have used 'catch' instead of 'with' for
your example - the combination of
- implementations allowing FunctionDeclaration as statement
- implementations differ in how such FunctionDeclarations
are hoisted
- ES/next limiting FunctionDeclaration hoisting to blocks
seems to imply that for some implementations, ES/next will
have different behaviour than ES5+FD-statements, for identical
program code (if I am reading this correctly, that is):
function Outer() {
var e = "Outer";
try { throw "Inner"; }
catch (e) {
function F() { log(e); } // some implementations hoist
// 'F' without closing over 'e';
F(); // those have to change here for ES/next
(function() { log(e); }());
log(e);
}
}
Outer();
My reading: some current implementations bind the 'e'
in 'F' to the 'Outer' 'e', while ES/next (and lexical scoping
intuition) will require a binding to the exception parameter.
Time for those implementations to change/raise warnings
now, before the switch? As is already recommended in the
current standard [12, note on page 86]..
I did not expect that.
Claus
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