Re: RFC: Deprecate libstdc++ Policy-Based Data Structures

[Tadeus Prastowo <tadeus dot prastowo at unitn dot it>]

Hi,

Knowing that Alex has stepped forward, I am interested in helping out
in this matter as well if you think that will help.  My experience in
maintaining a C++ library can be seen at
https://savannah.nongnu.org/projects/tice

-- 
Best regards,
Tadeus

On Tue, Jul 23, 2019 at 6:50 PM Alexander Kulkov <adamant.pwn@gmail.com> wrote:
>
> Sounds fair to me. Well, I personally might be interested in providing
> fixes and improvements for the code. I might even try to find some other
> people in community to contribute.
>
> PBDS is very well-thought library which I admired since the moment I saw
> it, and the possibility that it may completely go to waste kind of
> disappoints me, so I might put considerable effort to save it if that's
> possible. The major issue, though, is that I don't really know even how to
> start since I'm completely new to libstdc++ and have little experience with
> such huge projects. Any help and/or advice here in how I may contribute
> would be much appreciated.
>
> вт, 23 июл. 2019 г. в 19:21, Jonathan Wakely <jwakely.gcc@gmail.com>:
>
> > Sorry for the late reply that wasn't "tomorrow".
> >
> > On Tue, 9 Jul 2019 at 23:40, Alexander Kulkov wrote:
> > >
> > > Hi there! I hope, this message will go to where it's expected to go,
> > since
> > > I'm not really familiar with e-mail threads.
> > >
> > > I was the one who brought
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81806
> > > issue about sub-optimal implementation of split function in pbds. The
> > > reason why I did so is clearly described on this comment:
> > > https://codeforces.com/blog/entry/10355?#comment-157883
> > >
> > > So, a bit of story and context. Five years ago at codeforces.com
> > > (competitive programming website) someone eventually pointed out that
> > there
> > > is order-statistics tree in SGI library. It turned out to be very useful
> > in
> > > competitions since it is quite common type of queries to count number of
> > > elements less than k in set and unfortunately regular std::set doesn't
> > > provide such possibility although it would be extremely useful in
> > > competitions.
> > >
> > > I made two posts about pbds on codeforces to introduce them to community:
> > > https://codeforces.com/blog/entry/11080 and
> > > https://codeforces.com/blog/entry/13279. First one introduces
> > structures in
> > > general and second one describes how to modify them so they support
> > custom
> > > queries. Second one was not quite as popular, perhaps because it's not
> > much
> > > easier to comprehend and remember concept than simply write something
> > like
> > > cartesian tree on live contest. But the first one is pretty much alive,
> > > most recent comment was only 8 days ago.
> > >
> > > There was also another post (https://codeforces.com/blog/entry/60737)
> > > considering hash_map from pb_ds as a replacement for unordered_map since
> > > hash_map clearly outperform unordered_map. This one is also quite popular
> > > and well-known in competitive programming community.
> > >
> > > So speaking about "Do you actually use these containers?" I would say
> > that
> > > I often use tree_order_statistics_node_update in competitions, and in
> > > general specifically tree_order_statistics_node_update and hash_map are
> > > pretty popular in competitive programming community.
> > >
> > > Deprecating policy based data structures will deal much pain to some
> > > competitors because problems in which it's possible to use pbds instead
> > of
> > > custom balanced binary trees occur quite often and so now we'll have to
> > > implement bbst instead of using something out of the box.
> > >
> > > Not sure if you would consider this usage case as something "serious",
> > but
> > > well, I was asked, so I answered.
> >
> > Thanks for responding!
> >
> > I don't really care about this use case, sorry. If the programming
> > competition community were providing fixes or improvements for this
> > code I might be more inclined to keep supported it, but it seems like
> > we're just carrying around a huge chunk of code because it saves
> > people some time in some competitions. Presumably the competition code
> > is not reused, so there's no backwards compatibility issue here
> > either.
> >