Viability of Mercurial as an alternative to Git in 2024?

[PIERRE AUGIER]

I first wanted to react to a statement on Mercurial wheels on PyPI and it leads me to express my fear that Mercurial is not evolving towards a nice alternative to Git.

I describe few issues and try to think about what could be done to fix them.

----- Mail original -----
> De: "Alessandro Dentella" <sandro.dentella at gmail.com>
> À: "Uwe Brauer" <oub at mat.ucm.es>, "mercurial" <mercurial at mercurial-scm.org>
> Envoyé: Vendredi 19 Juillet 2024 09:36:14
> Objet: Re: ubuntu 24 (and most likely debian 12) does not allow to install evolve

> Il giorno gio 18 lug 2024 alle ore 16:45 Uwe Brauer via Mercurial < [
> mailto:mercurial at lists.mercurial-scm.org | mercurial at lists.mercurial-scm.org ]
> > ha scritto:
> 
> II don't really know which version of hg-git is ok for you, but I'm on Ubuntu
> 24:04 and I can tell you that 67.2 is the default that in fact does not work
> with evolve, so Idid exactly what was suggested by Sietze Browser::
> 
> sudo apt install pipx
> pipx install mercurial
> pipx inject mercurial hg-evolve hg-git
> 
> and I ended up with::
> 
> mercurial 6.8
> hg-git 1.1.3
> evolve 11.1.4
> 
> do you need something different?
> It was very fast as it uses wheels

Unfortunately, there is no Mercurial wheels on PyPI (see https://pypi.org/project/mercurial/#files)! I don't know any other big public open-source Python projects using extensions that do not upload wheels on PyPI. Nowadays, it is very simple. 

Even if I don't like it, I have to admit that it becomes more and more difficult to defend Mercurial. I start to feel that it does not make sense to teach Mercurial anymore. I see two main issues:

1. Setting up Mercurial with basic extensions (topics, hg-git, evolve) is TOO difficult and long for beginners (in particular compared to Git).

Python packaging is improving but Mercurial does not follow. Installation via pipx really makes sense for Mercurial and its extensions.

> pipx install mercurial
> pipx inject mercurial hg-evolve hg-git

should work **without compilation** (i.e. without Python headers and compilers) basically everywhere/everytime (of course on up-to-date/standard platforms with an up-to-date python). It should be checked that these commands lead to something reasonable on recent Windows, macOS and popular Linux distros. For example, on Windows, I thing there is by default neither vi nor any pager. Mercurial should be aware of that and at least print reasonable advice when such issues are detected.

The commands should lead to a correct user experience, in particular with an easy way to enable tab completion on popular terminals/shells. Modern mercurial should have a command to setup completion (something like https://pixi.sh/latest/#autocompletion). 

Using /usr/bin/python3 -m pip install (--user) or --break-system-packages are really bad practice.

Using hg-git or topics should not require writing by hands strange lines in ~/.hgrc. It is too difficult for beginners (terminal editors are hard for them) and for teaching it's sure that few students will do it wrong and get a buggy behavior. Nowadays, I wonder if hg-git and topics could not be automatically activated if they are installed for the Python used by Mercurial? Is there a good reason not to do that? It would be possible directly after `pipx inject mercurial hg-evolve hg-git` to clone Mercurial repositories using topics and Git repositories from Github.

If it does not make sense to auto activate topics and hg-git, Mercurial should have a simple interface (command line or maybe something like what we get with `hg commit -i`) to modify its user configuration.

More generally, with Git, one can run `git config --global user.name "Mona Lisa"`, which is convenient for beginners (much more than editing a file).


2. the difference between modern mercurial with topics and hg-git with bookmarks is an issue. We should not need to use/teach bookmarks to interact with a Git repository. Topics are much better. Most Git branches on Github which are not called master or main should be represented by topics (of course, there are exceptions which should be handled). I know that Dan Villiom Podlaski Christiansen works on a topic on this feature (https://foss.heptapod.net/mercurial/hg-git/-/merge_requests/101), which is planed for hg-git 2.0.0. However, I start to be less confident that it will be one day usable.

Moreover phases should be by default reasonable when working with Git repos (at least commits pushed on main/master should be public).


Sorry to tell all these negative statements but I feel that without changes and more focus on usability for beginners, I will have to stop to communicate on Mercurial and teach Mercurial. If this is a matter of founding, I may be able to help a bit and more generally we should organize ourself to get enough money to get these improvements.