content/blog/2009/05/what-i-hate-about-mercurial.markdown @ 6d36ebb4ecee

+++
title = "What I Hate About Mercurial"
snip = "Hg, I love you, but sometimes you bring me down."
date = 2009-05-29T19:51:05Z
draft = false

+++

This entry was inspired by [Jacob Kaplan-Moss][JKM], who was inspired by
[Titus][], who was inspired by [brian d foy][BDF]. 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.

[JKM]: http://jacobian.org/writing/hate-python/
[Titus]: http://ivory.idyll.org/blog/mar-07/five-things-I-hate-about-python
[BDF]: http://use.perl.org/~brian_d_foy/journal/32556?from=rss

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](http://selenic.com/mercurial).

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

<div id="toc"></div>

Configuration Through a Textfile
--------------------------------

This is one of the things that [git](http://git-scm.com/) people seem to like
to [bring up](http://jointheconversation.org/2008/11/24/on-mercurial.html):
"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`:

```ini
[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.

```console
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`:

```console
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:

```console
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](http://bitbucket.org/) is an awesome site, but
compared to [GitHub](http://github.com/) 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](http://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.