simple modules

[Sam Tobin-Hochstadt]

On Mon, Feb 1, 2010 at 8:28 PM, Kevin Curtis <kevinc1846 at googlemail.com> wrote:
> On Mon, Feb 1, 2010 at 11:13 PM, David Herman <dherman at mozilla.com> wrote:
>>
>> In terms of mechanism, that's not exactly what I had in mind, but in terms
>> of purpose that's the rough idea (specifically: "contexts are the means by
>> which access to platform resources are mediated" -- yes). Creating new
>> contexts would make it possible to restrict what modules can be imported, so
>> you could create "pure" execution contexts in which you could evaluate code
>> that would not have access to anything with interesting authority. This
>> would of course be host-dependent.
>>
>> Dave
>>
>
> Understood. Just a final point - modules that are imported with 'import' can
> be native modules? That is modules that are implemented in C++.

Right.  The host environment could provide some set of modules, along
with some naming scheme for referring to them.

> // compiler tries each in order
> import ['JSON', 'http://json.org/modules/json2.js'] as JSON;
> In the above case 'JSON' is a native module implemented in C++. If it
> doesn't exist a pure ES solution is used. From the end user point of view it
> is no matter if a module is implemented natively or via pure ES.

In the strawman, 'JSON' could be implemented in pure ES - as long as
it's declared in a place where the import statement can see it (in the
same Program, say).  In a modern browser, 'JSON' might be provided
natively, but the strawman doesn't commit to that.

> And it is possible, to configure a new context which will deny access to the
> native JSON module to code and imported modules within this context - if the
> developer desires.

That's the idea (due to Kris Kowal).

> Also, a general point. There has been discussion re ArrayBuffers. Would
> 'native modules' be a way to present this functionality to ECMAScript. As an
> alternative to putting them in the global object/namespace.
> import ModArrayBuffer; // imports ArrayBuffer, Int32Array, Int16Array etc
> buf = new ArrayBuffer(100);  // create 100-byte ArrayBuffer
> var ints = new Int32Array(buf);  // view that buffer as 32-bit integers
> var fourShorts = new Int16Array(buf, 20, 4);  // Starting at byte 20 in the
> buffer, create a 16-bit
> // end

Whatever we come up with for modules would be a good way to structure
all of the potential additions in Harmony - ArrayBuffers, Proxies,
etc.
-- 
sam th
samth at ccs.neu.edu