Hi John,
> Module declarations are only allowed at the top level of a script or module,
> but for convenience, they can nest within top-level blocks, and are hoisted
> to be in scope for the entire containing script or module.
>
> Can someone explain what this sentence means?
>
> To me it says: Module declarations MUST be outside of any function
> declaration, but you can declare modules pretty much anywhere as long as you
> don't expect to understand what happens when you do ;-).
Heh, that's not what it was supposed to mean, no. :) It means that you can
*only* nest module declarations inside plain block statements -- not under
conditionals, loops, functions, etc. For example:
<script type="harmony">
{
module C { ... }
module D { ... }
}
</script>
But I'm actually mostly convinced that allowing this little bit of nesting is a
bad idea anyway. The reason this relaxation was put in there was to support
REPL's, so that you could do multiline input with mutually recursive modules,
e.g.:
js> {
module A { ... B ... }
module B { ... A ... }
}
But I think this introduces too much complexity into the spec just to support
external tools, when those tools could probably pretty easily come up with
their own solution. For example, a REPL like Firebug or node.js could add
support for multi-line input with meta-commands such as:
node> .begin
... module A { ... B ... }
... module B { ... A ... }
... .end
And allowing the nesting, coupled with hoisting, introduces all the usual
headaches of hoisting like:
{
let M = 12;
{
module M { ... } // oh God, now what?
}
}
So having just explained this little detail, I'll now tell you that it's
probably going away anyway. :)
Dave
_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
