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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: How can one record component be local and another not?
Date: Tue, 5 May 2020 23:11:39 +0300
Organization: Tidorum Ltd
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Date: 2020-05-05T23:11:39+03:00
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On 2020-05-05 22:04, Niklas Holsti wrote:
> On 2020-05-05 20:32, hreba wrote:
>> Ok, with all your hints I came to the following solution:
>>
>> -- 
>> package Aux is
>>     type Integer_P is access all Integer;
>>     type Rec is limited record
>>        a: aliased Integer;
>>        p: Integer_P;
>>     end record;
>>
>>     procedure Init (r: access Rec);
>> end Aux;
>> -- 
>> package body Aux is
>>     procedure Init (r: access Rec) is
>>     begin
>>        r.p:= r.a'Access;
>>     end Init;
>> end Aux;
>> -- 
>> with Aux;
>> procedure Test is
>>     r:    aliased Aux.Rec;
>> begin
>>     Aux.Init (r'Access);
>> end Test;
>> -- 
>>
>> It compiles nicely, and then:
>>
>> frank@pc-frank:~/Temp/Test0$ ./test
>> raised PROGRAM_ERROR : aux.adb:4 accessibility check failed
>>
>> #@!!0ßx*~@!!!
> 
> Ok, apologies if I led you down the wrong path. I admit I did not build 
> a running program to check my suggestion of the "access" parameter, and 
> I have not myself often used this kind of code.
> 
> You should be able to get rid of this error by using 
> r.a'Unchecked_Access instead of r.a'Access, and then (I think) you can 
> return to using an "in out" parameter mode instead of "access" mode.

... but better make it "aliased in out" to ensure pass-by-reference.

I do agree with Dmitry that records with internal pointers-to-component 
should be "limited" or "controlled".

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .