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From: "Alejandro R. Mosteo" <alejandro@mosteo.com>
Newsgroups: comp.lang.ada
Subject: Re: package organization (is this doable?)
Date: Mon, 2 Jul 2018 10:23:06 +0200
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Xref: reader02.eternal-september.org comp.lang.ada:53501
Date: 2018-07-02T10:23:06+02:00
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On 29/06/2018 21:37, Simon Wright wrote:
> "Alejandro R. Mosteo" <alejandro@mosteo.com> writes:
> 
>> On 29/06/2018 18:34, Simon Wright wrote:
>>> "Alejandro R. Mosteo" <alejandro@mosteo.com> writes:
>>>
>>>> package Lib; -- Root package
>>>>
>>>> package Lib.Feat_1; -- Some feature
>>>>
>>>> package Lib.Feat_2; -- Another feature
>>>>
>>>> private package Lib.Impl; -- Things I want to keep secret,
>>>> conceptually they're in the private part of Lib IIUC.
>>>>
>>>> Am I right that it is impossible for Feat_1 and Feat_2 to communicate
>>>> using something that's private in Lib or Lib.Impl? That would mean
>>>> exposing those private types in their respective public parts, which
>>>> is a no go.
>>>
>>> Lib.Feat_1 & 2 can see the private part of Lib, and the public part of
>>> Lib.Impl.
>>>
>>> What's wrong with putting stuff in the public part of Lib.Impl? No one
>>> outside Lib can see it.
>>
>> in Lib.Feat_1, doing a "with Lib.Impl" results in error
>> "current unit must also be private descendant of Lib".
> 
> In the spec, yes (or, as you say, 'with private', but of course you
> can't make anything in the public part of Feat_1 (which is visible to
> clients) depend on the private package Impl.
> 
>> I can do (in Feat_1) a "private with Lib.Impl", but then I can use
>> these things only in private parts/body of Lib.Feat_1, which are also
>> out of bounds for Lib.Feat_2, and viceversa.
> 
> 'with Lib.Impl;' needs to be on Feat_*'s _body_.
> 
> So, put whatever you need Feat_1 to communicate to Feat_2 in Lib's
> private part or Impl's public part (remember, it's only public to Lib's
> body and Feat_*'s bodies.

Thanks, Simon, I think I see a way forward now thanks to your precisions.

Álex.

> 
> package Lib is
> private
>     J : Integer := 42;
> end Lib;
> 
> package Lib.Feat_1 with Elaborate_Body is
> end Lib.Feat_1;
> 
> package Lib.Feat_2 with Elaborate_Body is
> end Lib.Feat_2;
> 
> private package Lib.Impl is
>     K : Integer := 41;
> end Lib.Impl;
> 
> with Lib.Impl;
> package body Lib.Feat_1 is
>     A : Integer := J;
>     U : Integer := Impl.K;
> end Lib.Feat_1;
> 
> with Lib.Impl;
> package body Lib.Feat_2 is
>     B : Integer := J;
>     V : Integer := Impl.K;
> end Lib.Feat_2;
>