What I Hate About Mercurial

Posted on May 29th, 2009.

This entry was inspired by Jacob Kaplan-Moss, who was inspired by Titus, who was inspired by brian d foy. The premise is that you can't really claim to know much about a piece of software until you can name a few things you hate about it.

Jacob and Titus talked about Python, and so have a bunch of other people, so I figured I'd write about something a bit different: Mercurial.

I love Mercurial to death, but there are a few things about it that annoy me. Here they are, in no particular order.

  1. Configuration Through a Textfile
  2. "hg rm" is a Confusing Mess
  3. Addremove Can Track Renames But Won't Unless You Ask It Really Nicely
  4. Why the Hell Does Status Not Show Renames?
  5. Get Git Out of My Mercurial
  6. BitBucket Could Be Prettier
  7. Mercurial's Site Could Be Much Prettier
  8. But Hey, at Least It's Not Git!

Configuration Through a Textfile

This is one of the things that git people seem to like to bring up: "It doesn't have a command to set your username and email and such? Lame."

I personally don't mind editing a text file — vim ~/.hgrc really isn't that hard to type and the format is simple enough that you get the hang of it in about ten seconds. It forces you to know where the config file is, which is nice when the magic "Oh man, I could put my config files under version control!" moment strikes.

That said, this is on the list because I'd like to see a command to edit some of the common options just so people will stop complaining about something so trivial.

"hg rm" is a Confusing Mess

Here's part of the help for the hg rm command:

This only removes files from the current branch, not from the entire project history. -A can be used to remove only files that have already been deleted, -f can be used to force deletion, and -Af can be used to remove files from the next revision without deleting them.

What the hell? If -A won't remove files that are still present, and -f forces the files to be deleted, why the fuck does combining them mean the exact opposite of both?

I had to look up the syntax every single time I wanted to use this command, until I added this alias to my ~/.hgrc:

[alias]
untrack = rm -Af

Now I can use hg untrack whatever.py to stop tracking a file.

Addremove Can Track Renames But Won't Unless You Ask It Really Nicely

It took me a while to realize this, but Mercurial can actually record file renames — not just separate adds and removes — when using hg addremove. Here's what happens when you move a file and then use hg addremove normally to have Mercurial track the changes.

sjl at ecgtheow in ~/Desktop/test on default 
$ ls
total 16
-rw-r--r--  1 sjl    14B May 29 20:12 a
-rw-r--r--  1 sjl    12B May 29 20:12 b

sjl at ecgtheow in ~/Desktop/test on default 
$ mv b c

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg addremove
removing b
adding c

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg diff
diff --git a/b b/b
deleted file mode 100644
--- a/b
+++ /dev/null
@@ -1,1 +0,0 @@
-To you too!
diff --git a/c b/c
new file mode 100644
--- /dev/null
+++ b/c
@@ -0,0 +1,1 @@
+To you too!

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg commit -m 'Normal addremove.'

sjl at ecgtheow in ~/Desktop/test on default 
$

Now watch what happens when we tell Mercurial to detect renames when using hg addremove:

sjl at ecgtheow in ~/Desktop/test on default 
$ ls
total 16
-rw-r--r--  1 sjl    14B May 29 20:12 a
-rw-r--r--  1 sjl    12B May 29 20:12 c

sjl at ecgtheow in ~/Desktop/test on default 
$ mv c b

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg addremove --similarity 100
adding b
removing c
recording removal of c as rename to b (100% similar)

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg diff
diff --git a/c b/b
rename from c
rename to b

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg commit -m 'This time with rename detection.'

sjl at ecgtheow in ~/Desktop/test on default 
$

This time it notices the rename, and records it. The diff is far, far easier to read, and if a branch is merged in where someone else changed that file, the changes will follow it over.

The --similarity option is a percentage. I have an entry in my ~/.hgrc file to default that to 100, which means that renames will only be automatically detected if the files are identical. It's safer, but might not always catch everything.

I wish I had known this earlier or that Mercurial defaulted to 100% to catch the obvious renames.

And yes, I realize I could use hg rename to rename it and it would get recorded, but usually I'm moving files by some other method and using hg addremove to clean up later.

Now, while we're on the topic...

Why the Hell Does Status Not Show Renames?

Assuming they're recorded, I wish hg status would show that a file has been renamed. Here's what we get instead:

sjl at ecgtheow in ~/Desktop/test on default 
$ hg rename b c

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg stat
A c
R b

sjl at ecgtheow in ~/Desktop/test on default! 
$ hg diff
diff --git a/b b/c
rename from b
rename to c

No, hg status, it clearly wasn't an add and a remove, according to hg diff. Why doesn't hg status have a separate character for "renamed" files so we can tell them apart?

Get Git Out of My Mercurial

I hate that half of Mercurial's commands need a --git option to be really useful. Is there any reason not to make this the default format and have a --useless option for backwards compatibility?

I always add it to the defaults in my ~/.hgrc but it makes me feel kind of dirty when I do. It adds a bunch of unnecessary lines to the config file and confuses new people.

BitBucket Could Be Prettier

Don't get me wrong, BitBucket is an awesome site, but compared to GitHub it looks a bit dull and unappealing.

It's definitely more usable (how the hell do I view a graph of all branches/merges of a given repository on GitHub?) but there's something about GitHub's design that just makes it pop.

Mercurial's Site Could Be Much Prettier

Mercurial's site is ugly. Very ugly. It seems strange to me that the ugly version control system (git) has a fairly good-looking site while the much more elegant Mercurial has something that looks so boring and dated.

I know, mercurial-scm.org aims to fix this. Thank you from the bottom of my heart but please, hurry. The wiki is hurting my eyes.

But Hey, at Least It's Not Git!

All of those things annoy me, but they're small problems compared to the revulsion I get when I try to use git every so often.

Maybe that would be a good topic for another entry. At the very least it'll probably get me a ton of pageviews and comments saying: "Git's changed, man! It's not like it used to be, it's totally intuitive now! You just gotta learn how it stores the data!"

I learned, and I'll still take Mercurial despite the small annoyances.