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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Why doesn't Ada allow user-defined attributes?
Date: Sun, 23 Jul 2017 10:22:14 +0200
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Date: 2017-07-23T10:22:14+02:00
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On 2017-07-23 08:41, G.B. wrote:

> An order established by counting is not a property of the set it self,
> but may involve listing it somehow.

How exactly.

> A specific ordering is not needed for counting.

Not specific but some, any ordering is required. There is none. Full stop.

>>>> Lots of external things cannot be, e.g. a file you have no 
>>>> permission to read.
>>>
>>> A file needs to have been _counted_ byte by byte,
>>> or allocated using a known _count_ of bytes, etc.
>>> in order to have this length.
>>
>> No. File length is an attribute of a file. You don't need to read file 
>> or to allocate it.
> 
> Someone or something must have established the count by,
> well, counting.

It does not matter (even if it were true).

> Otherwise no file can meaningfully have
> that attribute (length) in the first place!

Surely it can. There is a system call "set file length". Get sources, 
look at the implementation. No counting there.

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