No, no, no. Let's get this myth out of the way that Mercurial Queues can somehow be part of a modern revision control system. Mercurial Queues are a simple stack of DUMB patches. The only reason why they are used is that often that is all you really need.

But the moment you need any kind of advanced functionality, such as say, something unimaginable like rebasing a Mercurial Queue against an upstream change that conflicts, you are suddenly dealing with tools that are no more advanced than diff and patch, and most certainly don't support any advanced operation on the patches that they juggle. I heard some modern tools like CVS support an advanced operation they call "merge". I'm still waiting until someone implements a usable version for Mercurial Queues.

So please, the moment you use Mercurial Queues in an argument, you've lost. Mercurial Queues are diff and patch in a fancy packaging, but with all the limitations of those. If your revision control system needs them to have the same functionality as another, you've lost.

The dirty secret is this: Mercurial users use Mercurial Queues because Mercurial got branching wrong. It's as simple as that.

In a way, the Git vs. Mercurial debate feels like vi vs. emacs all over again. Hardcore emacs users never quite understood the appeal of a modal editor; hardcore vi users couldn't quite understand how people lived with an input model that constantly moved their fingers off home row.

Emacs and vi both have their strengths and weaknesses. I've used both over the years sometimes trending to one or the other depending on the circumstances. As I've gotten to know both better, I understand the relative strengths better and know when it makes sense to use either. They're both good tools, and will both keep big user-bases for the foreseeable future.

Can I say the same about Mercurial and Git? That's a resounding NO.

I can accept that some holy wars can't have winners. But we should also be willing to accept that some tools can be just better than others.

With MQ, and especially with a versioned MQ directory, you have a great workflow for review-ready patches. And review-ready patches are what you are creating, after all, in most large projects: You do some work, you refactor that work N times, then you submit it for review, then you repeat that M times until it passes review and you push it to trunk.

With MQ, you can see the entire history of your set of patches. If you have a queue and you refactor two patches into one, you can go back in history in the versioned MQ dir to see what things were like before that. That is useful, because again, the "product" you are creating is a set of review-ready patches. So versioning the patches makes sense.

I understand that you can use git branches very effectively - I use git myself, not mercurial. However, if you use git to rewrite the history of your branch as part of your development process, AFAIK there is no way to go back in time and instantly see what your branch looked like at time K in the past, because history has been rewritten.

Rewriting history is great - you don't want to submit for review a huge list of patches that include bugfixes as you were working. You want to submit the final patches. But what if you do need to look at the state your work was in the past, before you rewrote history?

Mercurial Queues are bolted onto Mercurial and you can often see the cracks. Merging is my pet peeve which I've already mentioned. I think it's not controversial to say that it's a pain? I think that, in true Mercurial tradition, there's an extension in development for it now...

So why do we need to deal with this bolt-on and the resulting pain? Because Mercurial branches aren't good enough, or at least can't adequately support the workflow people need. Compare the amount of Mercurial users using mq to the amount of git users using quilt or equivalents.

I don't disagree with the abstract principle of operation of Mercurial Queues. I disagree with Mercurial as it is.

However, if you use git to rewrite the history of your branch as part of your development process, AFAIK there is no way to go back in time and instantly see what your branch looked like at time K in the past, because history has been rewritten.

1) It may be possible to do this with reflog. I don't know for sure because I haven't needed to do this yet. (I think the main problem is that by default reflog purges old history at some point)

2) You can simply create more branches as you go. i.e. replace qcommit by git checkout -b etc. Then push the final ones.

I've done this when I was submitting patches to a large git based project (perl5). The trick is to to the rebase and then re-tag your old branch. That way the old work is there if you need to reference it. Since it has a real live tag, it will not get garbage collected.

But git branches also have pain points. The only way to save history from before you rewrite history is to save branches, as you mentioned - but doing that manually every time you rewrite history is a pain.

In reality, 'rewriting history' comes down to things like:

* Creating a commit, then amending the commit message.

* Rebasing all of your current changes on top of a new version of master (basically re-applying all of your commits/patches on top of master).

* Fixing a typo creating a commit, and then squashing that into the original commit.

(Note: That these operations all happen on topic branches prior to being merged into master. Once you merge into master, or just publish for public consumption, then you should not be rewriting history at all.)

From my perspective, the view that git is useless because the ability to rewrite history means that valuable information is being lost is an extreme overreaction by people without much (or any) git experience.

If you want to hold this view, you should have rational examples of workflows where people will lose valuable information just as a matter of course.

However, that history can still be very useful: You might hit a variation on those bugs later, and seeing the original unrewritten history can help a lot in refreshing your memory on what you did there (and it can be even more helpful for someone else getting up to speed on the code trying to fix that bug). Losing the history after history rewriting isn't a good thing.

With your MQ workflow, you can only ever do this for your own patches.

This is incorrect. "hg rebase" is more advanced and smarter than diff and patch. Also, people arguing against Mercurial seem unaware of "hg collapse" which allows rewriting history in a way similar to git.

(However I would probably not use hg rebase on Mercurial queues, which are meant to be managed by mq extension commands.)

I think most of the git vs. mercurial debates are non-productive because proponents of one tool don't know the other tool well enough to argue against it.

You completely contradicted your own claim already.

This is exactly what I'm complaining about: Mercurial Queues are diff and patch. And you need Mercurial Queues for decent Mercurial workflows.

I think most of the git vs. mercurial debates are non-productive because proponents of one tool don't know the other tool well enough to argue against it.

I use Mercurial extensively and on a daily basis, so I think I'm qualified to talk about it. People who claim the complaint is invalid should do Mercurial users a favor and point out a workflow that avoids the issue. I'm still waiting (and manually merging all my patch queues whenever I get a conflict in a topmost patch).

Try this workflow.

You hit the nail on the head there. I wouldn't claim at all to know git well, despite having used it in numerous projects. On the other hand I felt like I "knew" Mercurial from the moment I picked it up. I've never written code to work around a problem (as the article suggests), and typically on the few occasions I've had problems I've remedied them by using Mercurial commands I already knew without even needing to look up documentation.

Opinions are clearly divided between two tools that perform the same task in very different ways. You can't please all of the people all of the time, long may both continue. More productive for everyone in my opinion would be ensuring bridge projects like hg-git become first-class citizens of the DVCS world.

The popularity of GitHub has made using Git a bit of a no-brainer, in the literal sense - a lot of Git users never really thought about the decision, they just needed some code from a Git repo and picked up Git along the way. I just don't see where people would be having the same experience with Mercurial. I've picked up several books recently where Git was taught in the first few chapters as a necessary precursor.

It appears to me that Git is the new SVN, the new version control tool that we're just stuck with whether we like it or not. I can think of much worse things.

That's not entirely true, in the sense that popular editors tend to have more extensions, syntax highlighting for more languages, auto-completion, etc... That helps draw in more users.

I just don't see where people would be having the same experience with Mercurial.

Well, there's bitbucket. IIRC some programming language communities have standardized on even more off-mainstream VCS.

But yeah, on the whole Git got an advantage in users somewhere along the way, and that's now self-reinforcing. It helps that there's no competition that's obviously better.