166 lines
4.6 KiB
Plaintext
166 lines
4.6 KiB
Plaintext
Nova Style Commandments
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=======================
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Step 1: Read http://www.python.org/dev/peps/pep-0008/
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Step 2: Read http://www.python.org/dev/peps/pep-0008/ again
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Step 3: Read on
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General
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-------
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- Put two newlines between top-level code (funcs, classes, etc)
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- Put one newline between methods in classes and anywhere else
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- Do not write "except:", use "except Exception:" at the very least
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- Include your name with TODOs as in "#TODO(termie)"
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- Do not name anything the same name as a built-in or reserved word
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Imports
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-------
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- Do not import objects, only modules
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- Do not import more than one module per line
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- Do not make relative imports
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- Order your imports by the full module path
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- Organize your imports according to the following template
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::
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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{{stdlib imports in human alphabetical order}}
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\n
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{{third-party lib imports in human alphabetical order}}
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\n
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{{nova imports in human alphabetical order}}
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\n
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\n
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{{begin your code}}
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Human Alphabetical Order Examples
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---------------------------------
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::
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import httplib
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import logging
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import random
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import StringIO
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import time
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import unittest
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import eventlet
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import webob.exc
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import nova.api.ec2
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from nova.api import openstack
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from nova.auth import users
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import nova.flags
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from nova.endpoint import cloud
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from nova import test
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Docstrings
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----------
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"""A one line docstring looks like this and ends in a period."""
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"""A multiline docstring has a one-line summary, less than 80 characters.
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Then a new paragraph after a newline that explains in more detail any
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general information about the function, class or method. Example usages
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are also great to have here if it is a complex class for function. After
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you have finished your descriptions add an extra newline and close the
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quotations.
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When writing the docstring for a class, an extra line should be placed
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after the closing quotations. For more in-depth explanations for these
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decisions see http://www.python.org/dev/peps/pep-0257/
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If you are going to describe parameters and return values, use Sphinx, the
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appropriate syntax is as follows.
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:param foo: the foo parameter
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:param bar: the bar parameter
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:returns: return_type -- description of the return value
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:returns: description of the return value
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:raises: AttributeError, KeyError
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"""
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Dictionaries/Lists
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------------------
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If a dictionary (dict) or list object is longer than 80 characters, its
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items should be split with newlines. Embedded iterables should have their
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items indented. Additionally, the last item in the dictionary should have
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a trailing comma. This increases readability and simplifies future diffs.
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Example:
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my_dictionary = {
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"image": {
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"name": "Just a Snapshot",
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"size": 2749573,
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"properties": {
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"user_id": 12,
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"arch": "x86_64",
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},
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"things": [
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"thing_one",
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"thing_two",
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],
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"status": "ACTIVE",
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},
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}
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Calling Methods
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---------------
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Calls to methods 80 characters or longer should format each argument with
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newlines. This is not a requirement, but a guideline.
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unnecessarily_long_function_name('string one',
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'string two',
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kwarg1=constants.ACTIVE,
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kwarg2=['a', 'b', 'c'])
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Rather than constructing parameters inline, it is better to break things up:
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list_of_strings = [
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'what_a_long_string',
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'not as long',
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]
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dict_of_numbers = {
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'one': 1,
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'two': 2,
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'twenty four': 24,
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}
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object_one.call_a_method('string three',
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'string four',
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kwarg1=list_of_strings,
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kwarg2=dict_of_numbers)
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Internationalization (i18n) Strings
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-----------------------------------
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In order to support multiple languages, we have a mechanism to support
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automatic translations of exception and log strings.
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Example:
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msg = _("An error occurred")
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raise HTTPBadRequest(explanation=msg)
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If you have a variable to place within the string, first internationalize
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the template string then do the replacement.
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Example:
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msg = _("Missing parameter: %s") % ("flavor",)
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LOG.error(msg)
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If you have multiple variables to place in the string, use keyword
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parameters. This helps our translators reorder parameters when needed.
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Example:
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msg = _("The server with id %(s_id)s has no key %(m_key)s")
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LOG.error(msg % {"s_id": "1234", "m_key": "imageId"})
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