Re: Taming constructors?

The WeakMaps of EcmaScript 6 provide even better support for rights
amplification. First, they enable the trivial creation of sealer/unsealers:

function makeSealerPair() {
  var wm = new WeakMap();
  return def({
    seal: function(payload) {
      var box = def({});
      wm.set(box, payload);
      return box;
    },
    unseal: function(box) {
      return wm.get(box);
    }
  });
}

Second, WeakMaps support better rights amplification patterns when used
directly, rather than through the sealer/unsealer abstraction. Compare the
MintMaker of <
http://erights.org/elib/capability/ode/ode-capabilities.html#simple-money>
and <http://research.google.com/pubs/pub40673.html>. The direct use of
WeakMaps for rights amplification enables the second to avoid the getDecr
function needed by the first.





On Wed, May 7, 2014 at 9:12 PM, Norman Hardy <norm-vN3M59HtaNxWk0Htik3J/[email protected]> wrote:

> I certainly think so. I began to implement the factory in Scheme and was
> reminded that Scheme lacks efficient synergy or any primitive to build it.
> http://cap-lore.com/Languages/Scheme/Synergy.html
> Some languages accidentally build it in, such as C++, OCaml, Smalltalk as
> part of their class structures.
> The original 1973 paper by Moriss suggests a simple sealer-unsealed
> primitive which I have not seen adopted in any wide spread language.
> Jonathan Rees has a variant of Scheme with efficient synergy.
>
> On 2014 May 6, at 18:55 , David Nicol <[email protected]> wrote:
>
>
>
>
> On Thu, May 1, 2014 at 9:07 AM, Kevin Reid <kpreid-M/[email protected]> wrote:
>
>>
>> I think that this is not a useful pattern in a capability language
>>
>
> the "factory pattern" is how one does constructors in a capability
> language, no?
>
>
>
>
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>
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-- 
    Cheers,
    --MarkM

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