packages

• lowercase
• lower_case_with_underscores

module

lower_case_with_underscores

c module

_single_leading_underscore

class

UpperCamelCase

function or method

• lower_case_with_underscores
• lowerCamelCase

variable

• lower_case_with_underscores
• lowerCamelCase

variable available in module

• _variableName
• put the variable into __all__

type variable

Capitalized_Words_With_Underscores

constant

UPPER_CASE_WITH_UNDERSCORES

exception; class name with suffix Error

UpperCamelCase+Error

special naming conventions

weak “internal use” ;from M import * doesn’t import those object; internal class method

_single_leading_underscore

avoid conflict through inherit; those name will be add class name as prefix

__double_leading_underscore

magic name

__double_leading_and_trailing_underscore__

conflict with keyword

keyword+_

lay-out

using 4 space instead of tab

max 79 character in one line

two lines between class or function ; one line between method or code block

space

using space between operators ,such as = < >

don’t use space in other place , such as [“a”]

import

don’t import more than two module in one line

import order: standard,third party,local

use absolute import ;explicit relative ;Implicit relative

Wildcard imports is not recommend; from module import *

docstrings for module

# module doc ; put in the head of module file
"""This is the example module.
This module does stuff.
"""
#
from __future__ import barry_as_FLUFL
#
__all__ = ['a', 'b', 'c']
__version__ = '0.1'
__author__ = 'Cardinal Biggles'
#
import os
import sys

docstrings for class

# class doc ; following the definition of class
"""
description:
"""

docstrings for function or method

# class doc ; following the definition of function or method
"""
description:
params:
return:
"""

comments for code block

# add comments before the code block
# Description : etc.

performance

string

string concat

using ‘‘.join() instead +

using string methods instead of string module

’‘.startswith() ‘‘.endswith()

check unicode string

isinstance(obj, basestring) in python2

compare type

isinstance(obj, type) instead of type(obj1) is type(obj2)

compare None

using is None,is not None instead of =

using def instead lambda

derive from Exception instead BaseException

exception

raise exception

#  recommend
raise ValueError('message') 
# not recommend
raise ValueError, 'message'

capture exception

# recommend
try:
    process_data()
except Exception as exc:
    raise DataProcessingFailedError(str(exc))

good try

# yes, limited line in try
try:
    value = collection[key]
except KeyError:
    return key_not_found(key)
else:
    return handle_value(value)   
# no, too much to do in try
try:
    # Too broad!
    return handle_value(collection[key])
except KeyError:
    # Will also catch KeyError raised by handle_value()
    return key_not_found(key)