Re: Writing an Operating System in Ada

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 15 Sty, 22:48, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:

> > The blob becomes useful only when it is loaded into memory.
>
> How does it?

By becoming a typed entity that is referenced within the actively
executed program. This is the moment when blob becomes useful.

> > The added value is that of name resolution.

> You don't need names for something, which is useless. You said it is
> useless when on the stick (which is of course wrong).

Ah, so we are again at the discussion style that will lead us nowhere.
But let's try for a while.

Several posts ago you have requested to execute actions on objects.
"Play" was an action on the movie - you wanted that. When I said that
the blob (a file, essentially) becomes useful when it is loaded into
memory, I meant that it is the interpretation of the blob that gives
it some requested capabilities.
You want it to "Play", but I might want it to blur or sharpen instead.
The point is that I can blur or sharpen a "movie" thanks to the fact
that I see it at a different level that you wanted to see it and that
would not be possible with pure-OO approaches (unless you allow
Unchecked_Conversion, but that brings us back to blobs anyway).

> > The purpose of the file system is to bring understanding to the
> > digital mess and the current file systems do their job pretty well.
>
> Sorry, but I don't know which kind of understanding you mean.

Apparently you do not understand. :-)

> In any case,
> "understanding" is not the purpose of the file system.

Well, I use it for this purpose.

> There are certain functionality a persistent store must provide. Among them
> enumeration, efficient indexing, naming, notifications, journaling,
> identification, distribution, authentication, consistency and so on. Modern
> file systems is a persistent store that fulfills some of these
> requirements. "Understanding" is not in this list.

Because you did not put it on that list. I'm not going to discuss it
this way.

http://en.wikipedia.org/wiki/File_System

"file system is a method of storing and organizing computer files and
the data they contain to make it easy to find and access them"

For me, "organizing" and "easy to find" are two aspects of
"understanding what is on the drive". In any case, I understand what I
have on my drive.

> > And the fact that my USB stick works everywhere shows that this
> > assumption is realistic. The assumption that the target OS is pure-OO
> > would not be.
>
> Assumption? It is not an assumption, it is a fact, that somebody sat down
> and wrote the implementation of FAT for the OS X1. Why he or someone else
> could not do this for an OO X2 persistence layer?

The only way to implement any persistence layer across different OSs
is to have it not coupled to any OS. If you have pure-OO OS (that is,
when *everything* in this system is OO) then it's persistence layer
cannot be implemented on other, non-OO OSs.

Current file systems (the ones with blobs) serve well as "common
denominators" and this is exactly their value.

> > Are you sure you are still living in a world where
> > "commercial" (whatever that means) is equivalent to "leading"?
>
> It is an equivalent to "measurable". You can measure involvement in serious
> projects by investments in.

That's one approach. Another is to measure involvement by
participation. In the age of social-this, social-that and social-
whatever, the accounting is different.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com

Database Access Library for Ada: www.inspirel.com/soci-ada