Emacs auto remove unused import statements in current python file

auto-remove.el

;;; auto-remove.el --- Auto remove unused functions in python

;;; Commentary:
;; Uses external tool autoflake to remove unused imports from a Python file.

;;; Code:

(defcustom python-autoflake-path (executable-find "autoflake")
  "Autoflake executable path.

Allows working with a virtualenv without actually adding support
for it."
  :group 'python
  :type 'string)

(defun python-remove-unused-imports ()
  "Use Autoflake to remove unused function.

$ autoflake --remove-all-unused-imports -i unused_imports.py"
  (interactive)
  (when (eq major-mode 'python-mode)
    (shell-command (format "%s --remove-all-unused-imports -i %s"
			   python-autoflake-path
			   (shell-quote-argument (buffer-file-name))))
    (revert-buffer t t t))
  nil)

(eval-after-load 'python
  '(if python-autoflake-path
       (add-hook 'before-save-hook 'python-remove-unused-imports)
     (message "Unable to find autoflake. Configure `python-autoflake-path`")))

(provide 'auto-remove)

;;; auto-remove.el ends here

@kracekumar Looks good but a few tips.

1. The elisp style guide mention not to use a line for just ).
2. Autoflake path should be customisable. Define a defcustom
   and add it to python group so that folks can just to M-x customize-group RET python RET. Use a path if available.

Code:

;; Auto remove unused functions in python
(defcustom python-autoflake-path (shell-command-to-string "which autoflake")
  "Autoflake executable path.

Allows working with a virtualenv without actually adding support
for it."
  :group 'python
  :type 'string)

(defun python-remove-unused-imports()
  "Use Autoflake to remove unused function"
  "autoflake --remove-all-unused-imports -i unused_imports.py"
  (interactive)
  (shell-command
   (format "%s --remove-all-unused-imports -i %s"
       python-autoflake-path
           (shell-quote-argument (buffer-file-name))))
  (revert-buffer t t t))

Discovered executable-find

;; Auto remove unused functions in python
(defcustom python-autoflake-path (executable-find "autoflake")
  "Autoflake executable path.

Allows working with a virtualenv without actually adding support
for it."
  :group 'python
  :type 'string)

Some error checking will also help.

(unless python-autoflake-path
  (error "Unable to find autoflake. Configure `python-autoflake-path`"))

@jaseemabid Thanks. Modified init.el accordingly. Also added before-save-hook.

@kracekumar The first time you visit a python buffer, it adds a before-save-hook to all buffers. So, saving a .el will still run this hook. Need to fix that part.

@jaseemabid I just encountered that. Finding right way to fix it.

Pushed a few patches here. https://gist.github.com/jaseemabid/3def1e104cbff09ad803

@kracekumar FYI, gists themselves are git repositories. Please fetch from my fork and have a look.

@jaseemabid: Thanks! It works.

@kracekumar Can you post errors raised by revert-buffer?

Is it happening the first time you are trying to save the file?

[Errno 2] No such file or directory: '/Users/j/tmp/test.py'  
Error: (error "Cannot revert nonexistent file /Users/j/tmp/test.py")
Wrote /Users/j/tmp/test.py

@kracekumar after-save-hook should solve it, right?

See patch 4d6871d here https://gist.github.com/jaseemabid/3def1e104cbff09ad803

4d6871d3881111c47fd35458770af817f5bafb01 
Author: Jaseem Abid <jaseemabid@gmail.com>
Date:   Mon Aug 18 00:55:17 2014 +0530

    Run hook after saving file

    - Makes sense to run flake after a file is saved with recent edits.

    - Fixes errors on reverting from non existent files. This can happen
      first time a file is saved.

Guys - this would be more useful if you could provide the full path to autoflake script in the comments of auto-remove.el . I am right now struggling to find autoflake, though I guess I wrote the original version of it :)

@pythonhacker You can do (setq python-autoflake-path "/this/is/where/autoflake/is.py")

PS: We made a repo https://github.com/kracekumar/missing-python-mode