Comment #4 on issue 327 by [email protected]: Remove or simplify support
for 'const'
http://code.google.com/p/v8/issues/detail?id=327
The semantics of "const", "let", and nested named function declarations in
ES-Harmony has
been settled for a long time. All of these bring their name into lexical
scope throughout their
enclosing block. Both "const" and "let" have a read barrier -- an attempt
to read the variable
before it has been initialized throws an error. Function names need no such
read barrier,
since they are initialized on block entry. See
http://wiki.ecmascript.org/doku.php?
id=harmony:const for how we apply these semantics to global code, where
global
declarations need to be reflected as properties of the global object.
For ES5-nonstrict, I expect each browser will continue to do whatever it
does today for each
of these cases. For ES5-strict, I think it is important that one either
reject these constructs
with an early error, or implement the anticipated Harmony semantics.
ES5-strict is gated by
an opt-in. We do not yet know whether there will be an additional opt-in
for Harmony. If not,
then it is important that language extensions accepted by ES5-strict not be
incompatible with
anticipated Harmony semantics.
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