python代码风格指南:pep8 中文版

本文档所提供的编码规范，适用于主要的Python发行版中组成标准库的Python代码。请参阅PEP关于Python的C实现的C编码风格指南的描述。

本文档和PEP257（文档字符串规范）改编自Guido的《Python Style Guide》一文，并从《Barry‘s style guide》添加了部分内容作为补充。

这篇风格指南随着时间的推移而逐渐演变，随着语言本身的变化，一些过去的约定已经过时，并确定了更多新的约定。

许多项目都有自己的编码风格指南。如果有任何冲突，优先使用该项目特定的指南。

# 与起始定界符对齐：
foo = long_function_name(var_one, var_two,
                         var_three, var_four)

# 使用更多的缩进，以区别于其他代码
def long_function_name(
        var_one, var_two, var_three,
        var_four):
    print(var_one)

# 悬挂缩进，必须增加一层缩进
foo = long_function_name(
    var_one, var_two,
    var_three, var_four)

# 不使用垂直参数时，第一行不能有参数。
foo = long_function_name(var_one, var_two,
    var_three, var_four)

# 参数的缩进与print()函数缩进相同。
def long_function_name(
    var_one, var_two, var_three,
    var_four):
    print(var_one)

#悬挂缩进不一定是4个空格。
# Hanging indents *may* be indented to other than 4 spaces.
foo = long_function_name(
  var_one, var_two,
  var_three, var_four)

# No extra indentation.没有额外的缩进
if (this_is_one_thing and
    that_is_another_thing):
    do_something()

# Add a comment, which will provide some distinction in editors.添加注释
# supporting syntax highlighting.
if (this_is_one_thing and
    that_is_another_thing):
    # Since both conditions are true, we can frobnicate.
    do_something()

# Add some extra indentation on the conditional continuation line.
#额外添加缩进，推荐
if (this_is_one_thing
        and that_is_another_thing):
    do_something()

# 右括号不回退，个人不推荐
my_list = [
    1, 2, 3,
    4, 5, 6,
    ]
result = some_function_that_takes_arguments(
    ‘a‘, ‘b‘, ‘c‘,
    ‘d‘, ‘e‘, ‘f‘,
    )

# 右括号回退
my_list = [
    1, 2, 3,
    4, 5, 6,
]
result = some_function_that_takes_arguments(
    ‘a‘, ‘b‘, ‘c‘,
    ‘d‘, ‘e‘, ‘f‘,
)

with open(‘/path/to/some/file/you/want/to/read‘) as file_1,      open(‘/path/to/some/file/being/written‘, ‘w‘) as file_2:
    file_2.write(file_1.read())

# No: operators sit far away from their operands.操作员坐在远离操作数的地方
income = (gross_wages +
          taxable_interest +
          (dividends - qualified_dividends) -
          ira_deduction -
          student_loan_interest)

# Yes: easy to match operators with operands.易于与操作数匹配的运算符
income = (gross_wages
          + taxable_interest
          + (dividends - qualified_dividends)
          - ira_deduction
          - student_loan_interest)

Yes: import os
     import sys

No:  import sys, os

from subprocess import Popen, PIPE

from . import sibling
from .sibling import example

from myclass import MyClass
from foo.bar.yourclass import YourClass

import myclass
import foo.bar.yourclass

# 括号里边避免空格
# Yes
spam(ham[1], {eggs: 2})
# No
spam( ham[ 1 ], { eggs: 2 } )

Yes: foo = (0,)
No:  bar = (0, )

# 逗号，冒号，分号之前避免空格
# Yes
if x == 4: print x, y; x, y = y, x
# No
if x == 4 : print x , y ; x , y = y , x

Yes:

ham[1:9], ham[1:9:3], ham[:9:3], ham[1::3], ham[1:9:]
ham[lower:upper], ham[lower:upper:], ham[lower::step]
ham[lower+offset : upper+offset]
ham[: upper_fn(x) : step_fn(x)], ham[:: step_fn(x)]
ham[lower + offset : upper + offset]

No:

ham[lower + offset:upper + offset]
ham[1: 9], ham[1 :9], ham[1:9 :3]
ham[lower : : upper]
ham[ : upper]

# Yes
spam(1)
dct[‘key‘] = lst[index]

# No
spam (1)
dct [‘key‘] = lst [index]

# Yes
x = 1
y = 2
long_variable = 3

# No
x             = 1
y             = 2
long_variable = 3