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From: Stephen Leake <stephen_leake@stephe-leake.org>
Newsgroups: comp.lang.ada
Subject: Re: yet another Ada web site?
Date: Fri, 14 Oct 2022 04:19:05 -0700
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On 2022-10-14 10:41, Fabien Chouteau wrote:
>> On Thursday, October 13, 2022 at 8:58:20 AM UTC+2, Dmitry A. Kazakov wrote:
>>> It seems so. Multiple versions at once are not supported. E.g. when you
>>> are working on two projects both dependent on different versions of
>>> another project:
>>>
>>> B -> A.1
>>> C -> A.2
>> Yes of course, different crates can depend on different version of
>> the same crate.
>
> It is about whether both A's can be installed and coexist on the same
> machine.

In Alire, "installed" means "checked out the source code into a local
directory".

If A depends on a system library that is a shared object file, and those
are different versions, then it depends on the OS; Debian can handle
this nicely, Windows only via separate directories and search paths.


>>> Or even the same project, e.g. when doing some migration from one
>>> version to another.
>> Not sure how you would do that? Link two different version of the
>> same library in an executable? That's not going to work.
>
> Same as above. You have B.1 -> A.1 and B.* -> A.2. You want to install
> both A.1 and A.2 and work on B.* while checking on B.1.

And the solution is the same as well.

> In the long gone time of common sense, a project code management
> system would use a virtual file system and map different parts of the
> projects graph onto a structure of folders arranged by versions. 

What prevents that now?

-- 
-- Stephe