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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: RFC: Prototype for a user threading library in Ada
Date: Sat, 25 Jun 2016 08:28:58 +0200
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Date: 2016-06-25T08:28:58+02:00
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On 2016-06-24 02:38, rieachus@comcast.net wrote:
> I don't get it.  If this is your "motivation":
>
>> The motivation is a two-liner. Let you have some consumer of data:
>>
>>    procedure Write (Buffer : String; Last : out Integer);
>>
>> It may take less than the whole string when called, but will take more
>> data later. So, the parameter Last. Now you want to write a program in a
>> *normal* way:
>>
>>    Write ("This");
>>    Write ("That");
>>
>> That's it.
>
> You may want to make your Last parameter in or in out, but that's a detail.

It is not a detail. The caller of Write does not know how much data the 
transport layer is ready to accept. That is the nature of non-blocking 
I/O. Write takes as much data it can and tells through Last where the 
caller must continue *later*.

A blocking busy-waiting wrapper looks this way:

    procedure Write (Buffer : String) is
       First : Integer := Buffer'First;
       Last  : Integer;
    begin
       loop
          Write (Buffer (First..Buffer'Last), Last);
          exit when Last = Buffer'Last;
          First := Last + 1;
       end loop;
    end Write;

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