Re: fyi, very interesting Ada paper OOP vs. Readability

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Wed, 16 May 2012 15:31:18 +0000 (UTC), NatarovVI wrote:

>>> Only data abstraction and modularity (without inheritance and, maybe,
>>> polymorphism) is good.
>> 
>> What is abstracted then?
>> 
>> P.S. There is no data without types.
> 
> What do you try to say?
> I try to say - there was "Data Abstraction" technology before OOP.

ADT was.

> it's like OOP but without inheritance and polymorphism.

A poor abstraction also, because it fails to capture any types relations,
beyond trivial containment.

> Only incapsulation. And that was good.

It wasn't good or bad. ADT predated richer algebras of types, as ad-hoc and
parametric polymorphisms did. There were obvious weaknesses in the ways ADT
worked in early languages. Some of them were overcame, some not until
today.

> inheritance break those good incapsulation.

How?

Containment breaks information hiding principle, separation of interface
and implementation, incapable to express referential semantics, enforces
tree-like structure of objects, break proper abstraction of semantically
integral types ... should I continue?

> polymorphism makes program reading context-dependent, that can be bad 
> also.

How reading can be context free?

> P.S. types is just alternative form of program, written purposely for 
> checking programmist's errors.

Type are not forms of program.

> So. Data CAN be "without types". Only this will be unsafe.
> 2+2=4. what type of 2 have? integer? enum? real? set of (2,4)?
> until we write we not know. and just cannot check.

Which is in self contradiction. If 2 is without a type why are you asking
which type it has?

Data does not exist without types, moreover they do not exist without the
agents interested in these data. In a larger context there are only values,
sets of values, types (sets of values bound by operations defined).

Data is a definite state of some input to some program. That state is
described in terms of values of defined types from the problem domain. So 2
could be data for the left argument of integer +, or an ASCII character
STX, or standard output descriptor, or whatever.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de