bug#44597: 26.3; bibtex should allow reverse sorting

[Roland Winkler]

On Sat Dec 19 2020 Francesco Potortì wrote:
> In my use case, I needed to sort about 100 bibtex entries in
> reversed date order, without any more criterion, and I had to
> resort to an external tool.  The reason was that i had to
> participate to a career selection where people was asked to
> provide a list of their own papers listed in reverse chronological
> order.
> 
> I had no need for a secondary sort key, so if I could just do that
> with bibtex.el it would have saved my day.

I believe in the usual world of BibTeX, this is a rather unique
situation.  BibTeX mode has been around for many years, when nobody
ever requested this.

> In fact, I had thought about writing a more generic patch, but
> with limited time on my hands, I preferred improving the current
> situation rather than trying to do the best.

I doubt that it is possible to provide a more generic patch that
could foresee these rare cases.

Actually, I just thought of a pretty cheap very different solution
for your problem, which is to regenerate the keys for your entries
such that the existing standard "sort by keys" approach gives you
whatever you need.  The autokey algorithm for generating the keys is
pretty powerful and easy to customize beyond the default.

> Again, that depends on the use case.  I am sure my patch can be useful
> even without a secondary sorting key and without a day being
> specified.

I believe we try here to predict and comment on rare scenarios which
is rather difficult.

I just checked the BibTeX page of emacswiki

 https://www.emacswiki.org/emacs/BibTeX

because I thought people might like to use it to collect code
snippets beyond the default.  It was last updated in 2014.
So it seems to me this is not an urgent matter.

> >Can you please test this?  Thanks.
> 
> I will, but please be patient.  I do this in my spare time, which is
> highly variable.

Thanks.  To simplify things, I just installed my patch for
user-defined sorting schemes.  Even if it does not provide an
easy-to-use solution, it should cover even the most exotic
scenarios.