Re: RFC: Adding BBDB to Emacs core

[phillip.lord@russet.org.uk (Phillip Lord)]

Stefan Monnier <monnier@IRO.UMontreal.CA> writes:

>> 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.


Yep. In practice, for my packages this would currently happen at either
24.1 (this is the oldest Emacs I can still compile, and even that
requires a bit of hacking) or 24.4 (the advice change). Being able to
leave a version at this point would be a good thing.


> 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, ...

Imagine I have left a package for an old version of Emacs. Now I find a
major security bug in the latest version, that I need to back-port to
the old version.

>> 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.

I haven't tested it yet; to my knowledge there is no routine testing of
ELPA against multiple Emacs versions.

Phil