Re: feature/integrated-elpa 4f6df43 15/23: README added

[Eli Zaretskii]

> From: address@hidden (Phillip Lord)
> Cc: Alain Schneble <address@hidden>,  address@hidden,  address@hidden
> Date: Wed, 19 Oct 2016 16:14:44 +0100
> 
> > The new version of Org will never do that.  So you are talking about
> > other packages that were not yet updated to follow suit, is that
> > right?  If so, is such explicit loading allowed?  If it's allowed,
> > it's a separate problem of dependencies between packages, and should
> > exist with any arrangement of directories, I think.
> 
> org has many add on packages, which do use explicit "require" forms to
> internal packages (if, for example, they extend an existing org
> backend).

Please see above: the problem is not within a single package, because
any package will always maintain internal requires in order.

> What I would expect is that an explicit (require 'org-html) would fail
> (i.e. report an error) when upgrading org to a version that does not
> include org-html. What actually happens is org-html from the old version
> gets loaded.

There should be no (require 'org-html) inside Org files in an Org
version that doesn't include org-html.

> load-path shadowing is I think, an ineffective mechanism for isolation
> between versions. Deleting old versions would work but not for core,
> admin installed, packages and is not-revertable.

Which is why load-path shadowing is the mechanism we should use, all
its disadvantages notwithstanding.

> Removing old versions from load-path is clean and the best solution,
> which is why package.el uses is.

That solution won't work with files in core.