Retrofitting objcaps

Matej Kosik kosik at
Thu Oct 19 08:24:38 UTC 2006

Hash: SHA1

Hi Alejandro

Alejandro F. Reimondo wrote:
>> Or am I wrong? Is it somehow possible
>> to implement ConstantPoint in
>> Smalltalk?
> If you need a point that do not move,
>  do not send #move messages to the point.

If I were the only one who would like to use that object than it would
be partially acceptable. But as soon as I would give others the
permission to that constant-point, I would like to *enforce* my
particular policy I had in mind.

If I do not want others to move that point then I do not want to give
them authority to move that point.

If I do not want other system to write more than 100 character log to
some file, then I do not want to give it authority to write more than
100 characters.

(other examples could be invented)

In Smalltalk such things are not enforcable. In E they are. Why is the
ability to enforce some policy important? It is usually useful when one
wants to cooperate with parties but he/she/it does not fully trust them.
In day to day reality this happens all the time.

> Nothing more efficient than the action
>  that has not been done.
> (if you have points that move and points that
>  do not move... it is very provable to have a
>  "failure" or a wrong point in the wrong place)

- --
Matej Kosik
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