Python

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Default modes

There are a number of python modes for Emacs. fgallina's python.el is the python.el included in Emacs 24.2 and onwards.

All-in-one solutions

emacs-for-python

emacs-for-python is a bundle of the above modes (and more), and it's an easy way to turn Emacs into a Python IDE.

emacs-for-python at github

Elpy

Elpy is a collection of elisp packages for Python too.

https://github.com/jorgenschaefer/elpy/wiki/Features


Refactoring

rope & ropemacs

Presentation

rope is a library for refactoring and manipulating Python code, pymacs is an interface between emacs lisp and python, and ropemacs is an Emacs interface to the rope library which uses rope and pymacs.

If you do some search and replace of code objects in your code and find it sometimes tricky, and/or you need to do it in more than one file, then you should consider a good tool of refactoring.

But Rope can do more than this simple example, it can:

  • Rename anything
  • Extract method/local variable
  • Change method signature
  • Perform cross-project refactorings
  • Support Mercurial, GIT, Darcs and SVN in refactorings

Rope can also help IDE's with:

  • Auto-completion
  • Finding definition location
  • Getting pydoc
  • Finding occurrences
  • Organizing imports (removing unused and duplicate imports and sorting them)
  • Generating python elements

Installation

Manually

You need to install rope with pip: 

   aptitude install python-rope

or 

   pip install rope

and then install ropemacs and pymacs (on ELPA).

rope homepage

ropemacs homepage and see the documentation on github.

With el-get

So an easy way is to use an el-get recipe: M-x el-get-install ropemacs. It installs and build Pymacs, rope and ropemacs. The difference from the solution using pip is that it setups the Emacs side of Pymacs correctly.

Auto-Completion

Jedi

Jedi.el is a Python auto-completion package for Emacs. It aims at helping your Python coding in a non-destructive way. It also helps you to find information about Python objects, such as docstring, function arguments and code location.

Jedi is simple to install and it works out of the box.

See screenshots and get the full documentation : http://tkf.github.io/emacs-jedi/released/

Jedi's official page: http://jedi.jedidjah.ch/en/latest/

Installation

Install Jedi.el via el-get, Marmalade or MELPA (see install for more info) and add this to your Emacs configuration: 

   (add-hook 'python-mode-hook 'jedi:setup)
   (setq jedi:setup-keys t)                      ; optional
   (setq jedi:complete-on-dot t)                 ; optional

or call M-x jedi:setup

Note: it's nice to use it in a python interpreter inside emacs :)

Anaconda

Anaconda-mode is a mode for code navigation, documentation lookup and completion for Python.

It runs on emacs 24.3 with python >= 2.6.

It provides:

  • context-sensitive code completion for Python
  • jump to definition
  • find references
  • view documentation
  • virtualenv management

The package is available in MELPA. For more information, read its documentation.

Code Checker

Flymake

flymake is a on-the-fly syntax checker for Emacs. We can use it alongside with flyspell.

To run pep8, pylint, pyflakes and unit-tests (with nose), you can be interested in using flymake-python.

Don't forget about pylint too.

Indexing sources: ctags, cscope, pycscope

Indexing sources allows you to do neat things, like going to the definition of a function or finding which functions are calling another one.

etags, ctags

Etags (Exuberant Ctags) generates an index (or tag) file of language objects found in source files that allows these items to be quickly and easily located by a text editor or other utility. A tag signifies a language object for which an index entry is available (or, alternatively, the index entry created for that object). Etags is a multilingual implementation of ctags.

The primary use for the tags files is looking up class/method/function/constant/etc declaration/definitions. Cscope is more powerful (see below).

usage

Generate the tags with this command at the root of your project: 

    find . -name "*.py" -print | etags -

it creates the file TAGS.

Note that projects like Projectile or Helm provide an integrated use of etags (finding one, re-generating the index, etc).

cscope

cscope is a much more powerful beast. While it operates on more or less the same principle (generating a file of useful metadata) it allows you do some fancier things like find all references to a symbol, see where a function is being invoked, etc.+ (you can find definitions as well).

It was originally designed for C and C++, but thanks to version 0.3 of pycscope, pythonistas can make use of it.

usage

The following commands should get you running: 

   apt-get install cscope
   pip install pycscope
   # in project base dir:
   find . -name '*.py' > cscope.files
   cscope -R

now install the xcscope emacs package with ELPA and require it: 

   (require 'xcscope)

When done, you can either enable the mode with cscope-minor-mode (which will add a menu you are free to explore) or call some functions like M-x cscope-find-global-definition, M-x cscope-find-functions-calling-this-function, etc.

Interactivity with helm-cscope

You can do all that interactively with helm-cscope: when you are on symbol, just call M-x helm-cscope-find-global-definition (for example) and enjoy the nice interactive interface.

Debugging

Ipdb, ipython debugger

If you call ipdb, the execution will stop and give a nice ipython-looking prompt. Just add `import ipdb; ipdb.set_trace()`

You can use the following to highlight this line, and not forget it : 

; Highlight the call to ipdb
; src http://pedrokroger.com/2010/07/configuring-emacs-as-a-python-ide-2/
(defun annotate-pdb ()
  (interactive)
  (highlight-lines-matching-regexp "import ipdb")
  (highlight-lines-matching-regexp "ipdb.set_trace()"))
(add-hook 'python-mode-hook 'annotate-pdb)

pdb track

If you use emacs-for-python given above, you can track your source code while debugging with pdbtrack.

A tool to use in a non-emacs terminal would be pdbpp

Other tools

Virtual environments

Some tools allow to apply the changes of virtual environment activation inside emacs:

  • pyvenv sets the python path, the environment for M-x compile, uses virtualwrapper's hooks.


Pymacs

Pymacs is an Emacs extension that enables the use of Python alongside with Emacs Lisp.

Pymacs homepage

Auto include import statements

Ropemacs (see above) is a plugin for performing python refactorings in emacs. It uses rope library and pymacs. It has rope-auto-import, so if you write 

   rmtree

and then execute M-x rope-auto-import, 

   from shutil import rmtree

is inserted at the top of the file.

Unfortunately Ropemacs can not do non-relative imports, it can only create imports of the "from X import Y" variety (if you type shutil.rmtree it doesn't write import shutil).

Sort import statements

See the py-isort Melpa package to automatically sort import statements.

See also

You'll be certainly interested in the following packages (that you will find on ELPA or MELPA):

  • Magit, a git interface. Emacs + git is magic : see magit
  • helm-pydoc to browse the documentation of installed packages and import one
  • pungi to integrate jedi, virtualenv and buildout.
  • other ELPA packages

If you're running Emacs 24, check out what is available in ELPA:

M-x list-packages
and see flymake-pyhon-pyflakes, flymake-shell, abl-mode (a python TDD minor-mode), nose (easy python test-running in emacs), pyregexp, python-magic and more.
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