Slicing some Python with Emacs
I have a new job and it’s quite probable that I will be doing Python for a lot of it. Which suites me just fine.
. . . except that I’ve been out of the loop in a while. Sure, I have written some Python in the past five years and some of it has been substantial but I feel out of the loop. Most of my simple scripts have been done in good ol’ Emacs and bigger projects have been done in Intellij IDEA with their amazing Python plugin.
As I started at the new digs, I installed Intellij on my shiny MacBook Pro, turned on Emacs mode . . . and was underwhelmed. I forgot that Emacs mode in Intellij on Mac leaves a lot to be desired —
C-Del for Cut,
Alt-P for paste? Ugh. A quick search shows that I’m not the only one complaining, but it’s not fixable.
I thought about Emacs and what I would miss about running things in Intellij IDEA. The biggies were:
- Syntax checking
- Running unit tests
- Auto-refactoring (Extract Variable, Method, etc)
These are things that are supposed to separate an IDE from a text editor. However, Emacs is an elegant weapon from a more civilized age. So the hunt is on to see what others have did while I was on my hibernation from Python.
I’ve tried to use the Rope library in the past and found it hard to setup. But I did note that it’s still actively developed and so I tried find to some example configs to
steal borrow from. That’s when I found Gabriele Lanaro’s excellent emacs-for-python collection. It included Rope, YA Snippet, and other goodies, all configured to work together in harmony.
I forked it, cloned it, and had a few problems, so I fixed them and Gabriele merged them back in. It still didn’t have unit test support, but I found nosemacs, which runs Nose on the Python unit tests.
In searching for something else, I stumbled into virtualenvwrapper, which are some helpers around the most excellent virtualenv utility, which creates a clean environment for Python development. These are used in emacs-for-python, so I put it in as well. I then stumbled into this post, which explains how to use the hooks in virtualenvwrapper to control Emacs. Woot!
So now my workflow is like this:
- type ‘workon something’, which will put my prompt in my “clean room” Python environment for the
project. My Emacs has also switched to that environment, including using that version of the Python interpreter.
- In Emacs, type
C-c m, which will run and report on all my unit tests in my current module
- In Emacs, type ‘C-c r ` to extract a new variable. Other commands exist for class, method, etc.
deactivateand my prompt moves away from my clean room, and my Emacs leaves too.
- when I go back to work on
somethingEmacs will remember the last buffers it worked on.
I put all these changes into my branch of emacs-for-python, and Gabriele has already pulled them in. They are available in HEAD on emacs-for-python
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