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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: set_index and and end_of_file with just a stream reference
Date: Sat, 20 Feb 2021 19:56:33 -0600
Organization: JSA Research & Innovation
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:s0rbv0$dss$1@gioia.aioe.org...
> On 2021-02-20 16:26, Mehdi Saada wrote:
>> In term of design, I have a file inside a protected type, to ensure 
>> validity for concurrrent readings/writings.
>
> This is illegal ARM 9.5.1 (8)

Formally, it is legal, but it isn't required to work - it might raise an 
exception if you do it. It can be made illegal in Ada 202x by setting 
Nonblocking => True on the protected type (that would have been better as 
the default from a programming perspective, but it would break a lot of 
existing code).

> Use a mutex (based on a protected object) or a monitor (based on a task) 
> for mutually exclusion of blocking operations.

Right.

                         Randy.