[cap-talk] Capability begginer questions

[Stiegler, Marc D]

Your cap-like references are useful, but they probably don't quite
qualify as capabilities in that, for it to be a capability, it should
probably be delivering an authority that the recipient can only get by
receiving such a capability. In C++, everything already has all the
authority it can eat. Your cap-like references are delivering authority
that the recipients already have ambiently. So they are useful for
modular OO design, but not for object-cap work.

--marcs 

> -----Original Message-----
> From: cap-talk-bounces at mail.eros-os.org 
> [mailto:cap-talk-bounces at mail.eros-os.org] On Behalf Of Rob Meijer
> Sent: Wednesday, October 03, 2007 7:09 AM
> To: General discussions concerning capability systems.
> Subject: Re: [cap-talk] Capability begginer questions
> 
> On Wed, October 3, 2007 15:24, Kevin Reid wrote:
> 
> > Assuming that you intend protected capabilities (which have 
> superior 
> > properties), there is no reason for the "key" to be random; 
> it might 
> > as well be a pointer or index referring to the 
> implementation of the 
> > capability (what is invoked/accessed when the capability is used).
> 
> I've been using function objects as such in C++, but never 
> realy considderd them to be true capabilities, but maybe they are?
> 
> That is, if we have a File class, define a cast operator to a 
> ReadFacet function object and a cast operator to a WriteFacet 
> function object, where the *Facet has as a member a reference 
> to the File object. These function objects, implementing some 
> operator()(...) method that simply invokes the proper method 
> of the File object, can than be 'used as' capabilities that 
> can be passed arround and invoked. I'm not realy sure if you 
> should brand these function objects capabilities, but for 
> practical purposes I think they are quite u usefull way to 
> use 'as' capabilities in C++.
> 
> Rob
> 
> 
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