Re: Capabilities interact nicely with Substructural Types and Reactivity

On 13 September 2013 13:41, David Wagner <[email protected]> wrote:
> On Thu, Sep 12, 2013, at 07:34 PM, David Barbour wrote:
>> DeepFrozen and Immutable are practical ways to solve real problems.
>>
>> But they are achieved by reflection and type systems, outside OOP and
>> object capabilities.
>>
>> Therefore, it is unreasonable to point at objects or capabilities as
>> providing the answer.
>
> Thanks for the explanation.  I am indeed interested in
> practical ways to solve real problems.  From my perspective,
> I don't care whether the credit for the solution is given to
> objects, capabilities, or to types; if the solution achieves
> the goals, I'm good with it.  Therefore, the current situation
> doesn't sound problematic to me.  I realize others may feel
> differently.
>
>> Further, DeepFrozen and Immutable do not have the same fine-grained
>> security-by-composition benefits as object capability model; they do not
>> enable the deep interleaving of trusted and untrusted code. They are very
>> blunt force tools.

To elaborate on Dr Barbour's statement here, the fact that the means
is reflection and type systems means that several of the composition
properties of caps do not apply.  One of the particularly nice things
about capabilities is that they distribute to different machines
across the network, machines that you may not actually trust.  Type
systems do not.  So deeply immutable objects could have methods that
effectively use other machines to represent state, right?

-- 
William Leslie

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