HACKING

Nova Style Commandments
=======================

Step 1: Read http://www.python.org/dev/peps/pep-0008/
Step 2: Read http://www.python.org/dev/peps/pep-0008/ again
Step 3: Read on

Imports
-------
- thou shalt not import objects, only modules
- thou shalt not import more than one module per line
- thou shalt not make relative imports
- thou shalt organize your imports according to the following template

::
  # vim: tabstop=4 shiftwidth=4 softtabstop=4
  {{stdlib imports in human alphabetical order}}
  \n
  {{nova imports in human alphabetical order}}
  \n
  \n
  {{begin your code}}


General
-------
- thou shalt put two newlines twixt toplevel code (funcs, classes, etc)
- thou shalt put one newline twixt methods in classes and anywhere else
- thou shalt not write "except:", use "except Exception:" at the very least
- thou shalt include your name with TODOs as in "TODO(termie)"
- thou shalt not name anything the same name as a builtin or reserved word
- thou shalt not violate causality in our time cone, or else


Human Alphabetical Order Examples
---------------------------------
::
  import httplib
  import logging
  import random
  import StringIO
  import time
  import unittest

  from nova import flags
  from nova import test
  from nova.auth import users
  from nova.endpoint import api
  from nova.endpoint import cloud

Docstrings
----------
  """A one line docstring looks like this and ends in a period."""


  """A multiline docstring has a one-line summary, less than 80 characters.

  Then a new paragraph after a newline that explains in more detail any
  general information about the function, class or method. Example usages
  are also great to have here if it is a complex class for function. After
  you have finished your descriptions add an extra newline and close the
  quotations.

  When writing the docstring for a class, an extra line should be placed
  after the closing quotations. For more in-depth explanations for these
  decisions see http://www.python.org/dev/peps/pep-0257/

  If you are going to describe parameters and return values, use Sphinx, the
  appropriate syntax is as follows.

  :param foo: the foo parameter
  :param bar: the bar parameter
  :returns: description of the return value

  """

Text encoding
----------
- All text within python code should be of type 'unicode'.

    WRONG:

    >>> s = 'foo'
    >>> s
    'foo'
    >>> type(s)
    <type 'str'>

    RIGHT:

    >>> u = u'foo'
    >>> u
    u'foo'
    >>> type(u)
    <type 'unicode'>

- Transitions between internal unicode and external strings should always
  be immediately and explicitly encoded or decoded.

- All external text that is not explicitly encoded (database storage,
  commandline arguments, etc.) should be presumed to be encoded as utf-8.

    WRONG:

    mystring = infile.readline()
    myreturnstring = do_some_magic_with(mystring)
    outfile.write(myreturnstring)

    RIGHT:

    mystring = infile.readline()
    mytext = s.decode('utf-8')
    returntext = do_some_magic_with(mytext)
    returnstring = returntext.encode('utf-8')
    outfile.write(returnstring)

Running Tests
-------------
The testing system is based on a combination of tox and testr. If you just
want to run the whole suite, run `tox` and all will be fine. However, if
you'd like to dig in a bit more, you might want to learn some things about
testr itself. A basic walkthrough for OpenStack can be found at
http://wiki.openstack.org/testr