[cap-talk] Capability begginer questions

[Jed Donnelley]

One other point that I think deserves to be mentioned
regarding beginner questions about capabilities relates
to their programming model, e.g. with regard to:

On 10/2/2007 11:48 AM, Matheus Morais wrote:
...
> 4 - I was playing with C++ and design a _very_ primary capability
> structure as follow:

If one just adds a bit of additional discipline to the
"object oriented" programming model it becomes a capability
model.  References to objects become capabilities if
passing such references as parameters is the only way
to provide access to their underlying objects.  Language
efforts like the E language:

http://www.erights.org/

and the Java subset "JoeE" suggest how the OO model
and the capability model are merging.

While some (e.g. Butler Lampson) have argued that capability
interfaces are impossibly awkward and inefficient due to the
need to pass so many permissions as parameters, I argue that
the success of the object oriented programming model suggests
otherwise.  I believe OO programming and capability based POLA
(Principle Of Least Authority) interfaces share a common long
term future.  Again I think this Wikipedia page:

http://en.wikipedia.org/wiki/Object-capability_model

is suggestive.

--Jed  http://www.webstart.com/jed/