Re: Capabilities interact nicely with Substructural Types and Reactivity

I wasn't speaking of creating any *particular class*, but rather the
ambient authority to `new` in general.

OOP enables arbitrary subprograms to create internal state and identity.
I.e. the concepts of "state" (including mutable private members) and
"identity" (which can include sealer/unsealer pairs, GUIDs, `eq` on object
references, or even construction of random values) are ambient authorities
in most OOP languages.

Private constructors have no effect on this at all.



On Thu, Sep 12, 2013 at 8:05 AM, Karp, Alan H <[email protected]> wrote:

>  Not being a languages guy, I didn’t follow very much of this, but one
> item caught my eye.****
>
> ** **
>
> **è **OOP assumes an *ambient authority* to create unique objects, and to
> create state that is initially exclusive (which is useful to control
> communication, and for implementation hiding). These authorities are useful
> for expressiveness. But  they can be problematic from certain security
> perspectives - e.g. when integrating untrusted code, it can be difficult to
> enforce deterministic behavior or certain forms of confinement. ****
>
> ** **
>
> When I want to control who can create new instances, I make the
> constructor private and hand out capabilities to an instance of a factory
> method.  Of course, that only works for languages that allow me to make the
> constructor private, e.g., Java but not JavaScript.****
>
> ** **
>
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>
> Alan Karp****
>
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