Re: Confused by y-or-n-p

[Eli Zaretskii <eliz@gnu.org>]

> From: Tassilo Horn <tsdh@gnu.org>
> Date: Wed, 06 Jan 2021 16:46:41 +0100
> 
> > Does installing from a binary distro (as opposed to from sources built
> > locally) remove previous versions nowadays?
> 
> Usually, yes.  Sometimes there is a package foobar-8.1.0 and additional
> foobar6-6.7.1, foobar7-7.9.12, i.e., installing foobar installs the
> current version (8.1.0) but separate packages are provided for older
> versions and you can have all of them installed in parallel, but that's
> mostly done for libraries where some other package only works with
> version 6 but not 7 or 8.

Not sure we are on the same page.  I meant the following situation:

  . I installed foobar, which brought me foobar-7.1.0, the latest
    version at that time
  . Time passes and I learn there's a newer version of foobar, 8.1.0.
    So I install foobar again, and that brings me foobar-8.1.0.

But did installing foobar-8.1.0 remove the installation of
foobar-7.1.0?  With many packages, the program executables that come
with the package have the same name 'foobar', so installing the new
one would overwrite the old one.  But building and installing Emacs
installs 2 executables: 'emacs' and 'emacs-MM.NN'; installing a new
version will overwrite 'emacs', but not the versioned 'emacs-MM.NN'
binary, so it needs to be explicitly deleted to get rid of it.  And
then there are versioned subdirectories of /usr/share and
/usr/libexec.

Do distros forcibly remove those versioned files and directories when
they install a new version?

> And from a distro packager's point of view, the additional
> user-convenience of enabling users to compare emacs version X against
> the current version surely doesn't justify the added maintenance costs.

In the case of Emacs, I see no additional costs if all they do is
refrain from removing the files belonging to the previous versions.
The costs are of the end-user.

Thanks.