Re: Latin_1 and portability

[Nick Roberts <nick.roberts@acm.org>]

Jeff C, wrote:

> "Bj�rn Persson" <bjorn_persson.spam-is-evil@sverige.nu> wrote in message
> news:20031214034629.3960d5a8.bjorn_persson.spam-is-evil@sverige.nu...

> > As a result, the file server can't know which files should be converted, it
> > can't know which format to expect from a certain client, and it can't know
> > which format a certain client needs; and there's not much AdaOS can do to
> > help.
> 
> Ah..But you miss the ultimate power of AdaOS. Since it does not exist and is
> never likely to exist, it is capable of claiming to perform all sorts of
> endless wonders...

It's true that AdaOS does not yet exist, and it surely will not for several 
years yet, but I remain as determined as ever to see it through, however 
long that takes.

Anyway, it's not really of importance to Bj�rn's point. I think all he 
meant to imply is that there's not much /some future operating system/ can 
do to help. In essence, that's quite correct. However, for the curious, 
AdaOS will have a way of coping with the problem (as it will have to, of 
course).

AdaOS will be object oriented, and files will be objects, and so strictly 
typed. Of course one type will be 'opaque binary', but all text files will 
have suitable types, parametised by encoding and character set.

I anticipate developing (and evolving) a piece of software in AdaOS which 
will use a strategy to guess the correct type of imported files. When 
obtaining a file by HTTP or FTP, it may be able to obtain a MIME type 
string, for example. For files coming from some kinds of systems, it may 
use a part of the name (the 'file type extension'). It may examine the 
file's contents. It might ask the user to supply or confirm the type. 
(Generally, the user will have to be asked for other information about the 
file anyway.)

Normally, every external file imported into a system will be permanently 
represented by an internal object. In this object will be stored a lot of 
information about the external file, including the (confirmed) type, and 
this type would generally be re-used whenever the file was re-accessed. (In 
fact, the file contents may be temporarily cached in the object anyway, 
according to parametised criteria.)

-- 
Nick Roberts
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