Is it possible to load multiple versions of the same system?

[Ian Tegebo]

On Fri, Apr 29, 2016 at 6:10 AM, Robert P. Goldman <rpgoldman at sift.net>
wrote:

> TBH, this seems to me like a pretty esoteric use case: I'm curious about
> how and when you encounter it.
>

Elsewhere, it happens in large projects where two direct dependencies
themselves depend on different versions of the same library.  I haven't had
this happen to me in CL, but I expect it to happen if exact version
matching were to become prevalent.

In reading this list, and elsewhere, I understand that versioning becomes
controversial.  I've experienced both sides of the problem where you either
under or over specify the versions of dependencies.  Exact version matching
is a useful tool to limit the impact of upstream changes.  However, it does
induce trivial domino-updates.  At Amazon, I got used to some tooling and
process that reduces the overhead, while also seeing the turmoil caused by
teams having to support old versions (they'd pinned/used-exact and would
never have "the resources" to update).


> If you're interested in cool language features, that's one thing, but I
> can't imagine as an engineering matter that you couldn't hack around the
> few times this would happen.
>

While I am interested in cool [features] for HOT languages [1], I recognize
the pragmatic approach is sort out the upstream divergence and find some
workaround - I'm not arguing one way or the other - just wondered whether
and how one might sort it out at the system-builder layer.

[1]: http://dl.acm.org/citation.cfm?id=277730

-- 
Ian Tegebo
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