Protected vs. unprotected objects

Protected vs. unprotected objects

[Terry Devine]

I'd like to be able to switch back and forth between protected and
unprotected objects to be able to experiment with protection at various
levels of a data structure.  However, if I read the LRM correctly, it
would require major trauma (e.g., object.routine <-> routine(object)) .
Does anyone have a good solution?

Terry Devine

Re: Protected vs. unprotected objects

[Tucker Taft]

Terry Devine (tdevine@mitre.org) wrote:

: I'd like to be able to switch back and forth between protected and
: unprotected objects to be able to experiment with protection at various
: levels of a data structure.  However, if I read the LRM correctly, it
: would require major trauma (e.g., object.routine <-> routine(object)) .
: Does anyone have a good solution?

Probably use limited private types at each level of abstraction.
The full type definition for a limited private type can be a protected type.
The visible operations of the limited private type can just turn around
and call the protected operations where appropriate.  In other words,
use routine(object) everywhere, and only in the definition of "routine"
would you write "object.protected_routine(..)".  You could inline
the visible non-protected routines for efficiency, if you want.

: Terry Devine

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA

Re: Protected vs. unprotected objects

[Anonymous]

On Wed, 17 Dec 1997 17:00:04 -0500, Terry Devine <tdevine@mitre.org>
wrote:

> I'd like to be able to switch back and forth between protected and
> unprotected objects to be able to experiment with protection at various
> levels of a data structure.  However, if I read the LRM correctly, it
> would require major trauma (e.g., object.routine <-> routine(object)) .
> Does anyone have a good solution?

Well, of course. Structure your application in terms of
Abstraction.Operation. "Abstraction" is a package. In the body of the
package, you can implement "Operation" in terms of a protected operation
or not, however you please, without major trauma to the rest of your
system.

This is a software engineering technique called "information hiding."

Jeff Carter  PGP:1024/440FBE21
My real e-mail address: ( carter @ innocon . com )
"I waggle my private parts at your aunties."
Monty Python & the Holy Grail

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Re: Protected vs. unprotected objects

[Mats Weber]

Terry Devine wrote:
> 
> I'd like to be able to switch back and forth between protected and
> unprotected objects to be able to experiment with protection at various
> levels of a data structure.  However, if I read the LRM correctly, it
> would require major trauma (e.g., object.routine <-> routine(object)) .
> Does anyone have a good solution?

One more vote in favor of package types :-)