Re: org 9.2.6 and org 9.1.9

[Tim Cross <theophilusx@gmail.com>]

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There is a very important rule which must be followed wrt org-mode
installation. It is critical that no version of org is already loaded
before installing a new version. This can be quite tricky as many of us
have org setups which automatically load some org functionality without
explicitly opening an org file or agenda view (for example, you might be
using an org add-on for email). Situation is worse if we are loading org as
part of our init.el.

I'm also not sure that tweaking the load-path order is sufficient if your
installing org via M-x package-install as there is a 'chicken and egg'
problem with the initial install. If your init.el file is loading org
functionality and you only have the built-in org version installed, that
version will be loaded before you run package-install. Probably works if
you install via your init.el though.

I've found the safest thing to do is only use autoload or use-package with
deferred loading for org and whenever updating org (I use the
org-plus-contrib package from the org elpa repo) only update immediately
after a fresh restart of emacs and before doing anything else.  Failing to
do this often results in a broken build as you get a set of new org elc
files which contains definitions from two different org versions. When the
versions are only different in minor version numbers, this mixed build may
not even be noticeable, but when major version differences exist, you get
the symptom of broken functionality, missing definitions or unbound symbols.

The situation is made worse by package maintainers specifying the latest
org version rather than the version built into Emacs when the bundled
version would be sufficient.

It took me a while to structure my init.el file such that no org
functionality was loaded until I used something which depends on it.
However, once I did, provided I only update org in a fresh new session, all
works flawlessly. I found use-package package really helped with this.



On Wed, 27 Nov 2019 at 06:22, Nick Dokos <ndokos@gmail.com> wrote:

> Jean-Christophe Helary <jean.christophe.helary@traduction-libre.org>
> writes:
>
> > org 9.1.9 is a built-in
> >
> > but org 9.2.6 comes as a dependency to some packages and having both
> installed creates conflicts.
> >
>
> What conflicts are you seeing? I have the built-in 9.1.9 org that
> comes with emacs but I run (close to) latest master and I see no
> problems: the only thing I do is to set my load-path to point to the
> right place (and make sure that that setting precedes the
> /usr/local/share/emacs/27.0.50/lisp/org setting that emacs adds):
>
>     (add-to-list 'load-path (expand-file-name "~/elisp/org-mode/lisp"))
>
> Although that has been enough for me, it's probably safer to delete
> from load-path all other org entries, thereby making the built-in
> version invisible to emacs - in my case, I just have the one:
>
>    (delete "/usr/local/share/emacs/27.0.50/lisp/org" load-path)
>
> That way, if you happen to do something like `(require 'old-org-req)'
> with a requirement that is not satisfied by current org, but is
> satisfied by the built-in org, you'd get an error, rather than getting
> a mixed installation.
>
> > Why does that happen ?
> >
> > Can't 9.2.6 override 9.1.9 ? It's not the first time I have issues
> > with that situation and that's extremely confusing. What is the best
> > way to solve that ?
> >
>
> I think the above should be enough (and IME it is), but maybe someone can
> think of other things that might trip one up.
>
> --
> Nick
>
> "There are only two hard problems in computer science: cache
> invalidation, naming things, and off-by-one errors." -Martin Fowler
>
>
>

-- 
regards,

Tim

--
Tim Cross

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