Re: RFC: Adding BBDB to Emacs core

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

> As a package author, I have two choices here: either I move to Emacs-27
> and ditch Emacs-26 support. Or I have to put runtime conditional logic
> which supports both.

That's right.

> I think package authors should have the choice of freezing the
> Emacs-26 version of their package when Emacs-27 comes out.

There's a case to be made for allowing ELPA archives to exports several
versions of a package at the same time, so older Emacsen can still
install the old version of a package without having to download the old
version by hand.

But I'm not moved by your scenario: adding runtime conditional logic has
been standard procedure "for ever" and comes with all kinds of
advantages, such as the ability for older Emacsen to benefit from other
improvements in the newer versions of your package, or an easier way to
install&use the package with several different versions of Emacs at the
same time, ...

> This situation would get worse if we have an "unstable" version of
> ELPA.

I don't see why: "unstable" is just a preview of what will be "stable"
a few weeks/months later and packages usually preserve compatibility at
least with Emacsen that are a few years old.

> I bet that there is some package already that depends on Emacs-27
> at the bleeding edge.

I strongly doubt it.


        Stefan