Add information about writting yourself rules, revert no_command changes

README.md

@@ -61,6 +61,40 @@ And add to `.bashrc` or `.zshrc`:
 alias fuck='$(thefuck $(fc -ln -1))'
 ```
 
+## Creating your own rules
+
+For adding your own rule you should create `your-rule-name.py`
+in `~/.thefuck/rules`. Rule should contain two functions:
+`match(command: Command, settings: Settings) -> bool`
+and `get_new_command(command: Command, settings: Settings) -> str`.
+
+`Command` have three attributes: `script`, `stdout` and `stderr`.
+
+`Settings` is `~/.thefuck/settings.py`.
+
+Simple example of the rule for running script with `sudo`:
+
+```python
+def match(command, settings):
+    return ('permission denied' in command.stderr.lower()
+            or 'EACCES' in command.stderr)
+
+
+def get_new_command(command, settings):
+    return 'sudo {}'.format(command.script)
+```
+
+[More examples of rules](https://github.com/nvbn/thefuck/tree/master/thefuck/rules),
+[utility functions for rules]((https://github.com/nvbn/thefuck/tree/master/thefuck/utils.py)).
+
+## Settings
+
+The Fuck have a few settings parameters:
+
+* `rules` – list of enabled rules, by default all;
+* `command_not_found` – path to `command_not_found` binary,
+by default `/usr/lib/command-not-found`.
+
 ## Developing
 
 Install `The Fuck` for development:

setup.py

@@ -2,7 +2,7 @@ from setuptools import setup, find_packages
 
 
 setup(name='thefuck',
-      version=1.3,
+      version=1.4,
       description="Magnificent app which corrects your previous console command",
       author='Vladimir Iakovlev',
       author_email='nvbn.rm@gmail.com',

tests/rules/test_no_command.py

@@ -1,7 +1,7 @@
 from subprocess import PIPE
 from mock import patch, Mock
 import pytest
-from thefuck.rules.no_command_apt import match, get_new_command
+from thefuck.rules.no_command import match, get_new_command
 from thefuck.main import Command
 
 
@@ -21,23 +21,30 @@ vom: command not found
 
 @pytest.fixture
 def bins_exists(request):
-    p = patch('thefuck.rules.no_command_apt.which',
+    p = patch('thefuck.rules.no_command.which',
               return_value=True)
     p.start()
     request.addfinalizer(p.stop)
 
 
+@pytest.fixture
+def settings():
+    class _Settings(object):
+        pass
+    return _Settings
+
+
 @pytest.mark.usefixtures('bins_exists')
-def test_match(command_found, command_not_found):
+def test_match(command_found, command_not_found, settings):
-    with patch('thefuck.rules.no_command_apt.Popen') as Popen:
+    with patch('thefuck.rules.no_command.Popen') as Popen:
         Popen.return_value.stderr.read.return_value = command_found
-        assert match(Command('aptget install vim', '', ''), None)
+        assert match(Command('aptget install vim', '', ''), settings)
         Popen.assert_called_once_with('/usr/lib/command-not-found aptget',
                                       shell=True, stderr=PIPE)
         Popen.return_value.stderr.read.return_value = command_not_found
-        assert not match(Command('ls', '', ''), None)
+        assert not match(Command('ls', '', ''), settings)
 
-    with patch('thefuck.rules.no_command_apt.Popen') as Popen:
+    with patch('thefuck.rules.no_command.Popen') as Popen:
         Popen.return_value.stderr.read.return_value = command_found
         assert match(Command('sudo aptget install vim', '', ''),
                      Mock(command_not_found='test'))
@@ -47,9 +54,9 @@ def test_match(command_found, command_not_found):
 
 @pytest.mark.usefixtures('bins_exists')
 def test_get_new_command(command_found):
-    with patch('thefuck.rules.no_command_apt._get_output',
+    with patch('thefuck.rules.no_command._get_output',
                return_value=command_found.decode()):
-        assert get_new_command(Command('aptget install vim', '', ''), None)\
+        assert get_new_command(Command('aptget install vim', '', ''), settings)\
             == 'apt-get install vim'
-        assert get_new_command(Command('sudo aptget install vim', '', ''), None) \
+        assert get_new_command(Command('sudo aptget install vim', '', ''), settings) \
             == 'sudo apt-get install vim'

thefuck/rules/no_command.py

@@ -1,25 +1,26 @@
 from subprocess import Popen, PIPE
 import re
-from thefuck.utils import which
+from thefuck.utils import which, wrap_settings
 
 
-def _get_bin(settings):
+local_settings = {'command_not_found': '/usr/lib/command-not-found'}
-    return getattr(settings, 'command_not_found', '/usr/lib/command-not-found')
 
 
 def _get_output(command, settings):
     name = command.script.split(' ')[command.script.startswith('sudo')]
-    check_script = '{} {}'.format(_get_bin(settings), name)
+    check_script = '{} {}'.format(settings.command_not_found, name)
     result = Popen(check_script, shell=True, stderr=PIPE)
     return result.stderr.read().decode()
 
 
+@wrap_settings(local_settings)
 def match(command, settings):
-    if which('apt-get') and which(_get_bin(settings)):
+    if which(settings.command_not_found):
         output = _get_output(command, settings)
         return "No command" in output and "from package" in output
 
 
+@wrap_settings(local_settings)
 def get_new_command(command, settings):
     output = _get_output(command, settings)
     broken_name = re.findall(r"No command '([^']*)' found",

thefuck/utils.py

@@ -1,7 +1,10 @@
+from functools import wraps
 import os
 
 
 def which(program):
+    """Returns `program` path or `None`."""
+
     def is_exe(fpath):
         return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
 
@@ -17,3 +20,24 @@ def which(program):
                 return exe_file
 
     return None
+
+
+def wrap_settings(params):
+    """Adds default values to settings if it not presented.
+
+    Usage:
+
+        @wrap_settings({'apt': '/usr/bin/apt'})
+        def match(command, settings):
+            print(settings.apt)
+
+    """
+    def decorator(fn):
+        @wraps(fn)
+        def wrapper(command, settings):
+            for key, val in params.items():
+                if not hasattr(settings, key):
+                    setattr(settings, key, val)
+            return fn(command, settings)
+        return wrapper
+    return decorator