Python Code format specification

Current specifications are based on pep-0008

Basic formatting indentation

Indent with 4 spaces

Line width

Try not to exceed 80 characters per line of code

Reason:

• This is helpful when looking at Side-by-side diff.
• Easy to view code under the console
• Too long could be a flawed design

Line break

Python supports line breaks in parentheses. There are two kinds of situations.

1. The second line indents to the beginning of the parentheses

= Long_function_name (Var_one, Var_two,                         Var_three, Var_four)

2. The second line indents 4 spaces, applies to the case where the starting parenthesis wraps

Long_function_name (        var_three,        print (var_one) 

With backslash \ wrapping, the two-dollar operator, and so on, + . should appear at the beginning of the line and align with the previous row, . = or indent 4 spaces. Long strings can also be wrapped in this method.

 foo = variable_with_long_name + another_variable + V Ariablesession.query (MyTable). filter_by (id=1). One () This_is_a_very_long (Function_call,  ' with many parameters print < Span class= "Pl-pds" > ' Hello,  '  ' % s %s! % ( ' Harry "< Span class= "Pl-pds" > ' Potter "         

List or tuple of multiple elements, wrapping after starting brackets, 4 spaces in the second line

= [' This was the first    ' Set of items' with ' + more items ' to come ' "This'] 

A compound statement is prohibited, that is, a row contains multiple statements:

# Yesdo_first () Do_second () Do_third ()# Nodo_first ();d o_second ();d o_third (); 

if/for/whileBe sure to change the line:

# Yes' blah': do_blah_thing ()# no' blah': do_blash_thing ()    

Blank Line

• Two empty lines between the module-level function and the class definition;
• An empty line between class member functions;
• Do not use too many contiguous blank lines to differentiate the logical blocks of code

A: "" "This is    a simple docstring.    " "" " __init__ (hello (passhello (%s!  % NamePass        

• Multiple empty rows can be used to separate multiple sets of related functions
• A function can use a blank line to separate logically related code

Expression spaces

• Unary operators do not add spaces
• On each side of the two-dollar operator, empty one lattice [=,-,+=,==,>,in,is not, and] :

# Yesexp=-1.05i= I+1submitted+=1x= X*2-1hypot2 = x * x + y * yc = (a + b) * (a -B) # noexp = -1.05i< Span class= "pl-k" >=i+1submitted += 1x = x*2 - 1hypot2 = x*x + y*yc = (A+b) * (A-b)     

• The argument list of the function, , followed by a space

# Yescomplex (pass# nocomplex (Real,pass     

• In the parameter list of the function, do not add spaces between the default equals sign

# Yescomplex (imag=passcomplex (pass     

• After opening parenthesis, do not add extra space before closing parenthesis.

# yesspam (ham[= My_list[index]# nospam (ham[= my_list[index]  

• No extra spaces before the opening parenthesis of a dictionary or List object

# yesdict[' key= List[index]# nodict [' Key= list [index]    

• Do not use extra spaces for Zishing value statements

33

Comparison

• Use variable on left, constant in right
• Do not display a comparison of the pairs True , False
• Negative comparisons are adopted foo not in bar in the form of, rather thannot foo in bar
• Use the instance(a, C) type check for the instance, nottype(A) is C

# YesIf method==' MD5': pass if not foo: passif Foo not in bar: PassIf instance (A, C): Pass# N oif ' md5' = = method: passif foo = = False: pass if not foo in  ba R: Passif type (A) is C: pass          

Quotes

Simply put, the natural language uses double quotes, the machine is marked with single quotes, so most of the code should use single quotes

• Use double quotation marks for natural language"..."
  such as error messages; In many cases Unicode, useu"你好世界"
• machine identification using single quotes ‘...‘ such as key in Dict
• Regular Expressions use native double quotesr"..."
• document characters use three double quotation marks"""......"""

Import statement

• Import statements should be written in branches

# Yesimport OSimport sys# noimport sys,os# YesPIPE     

• The import statement should use absolute import

# Yesimport Bar# noimport bar  

• The import statement should be placed at the head of the file, after the module description and docstring, before the global variable;
• Import statements should be ordered in order, separated by a blank line between each group

Import OSimport sysimport msgpackimport zmqimport foo   

• When you import class definitions for other modules, you can use relative imports

Import MyClass

• If a naming conflict occurs, you can use the namespace

Import Foo.barbar.Bar () Foo.bar.Bar ()

Comment Block Comment

#After the number is empty, the paragraphs are separated by a blank line (the same number is required # )

# block Comment  # block Comment ## block Comment # block comment   

Line Comment

Use at least two spaces and statements to separate, using meaningful annotations

1  # border Bold one  pixel

DocString

The docstring specification is described in detail in PEP 257, where the two points are the most:

1. All public modules, functions, classes, methods, should be written docstring. Private methods are not necessarily required, but a block comment should be provided after the def to illustrate.
2. The docstring "" "should have a single line unless this docstring has only one row.

"" "Return a foobarOptional Plotz says to frobnicate the Bizbaz first." " "" " oneline docstring    " ""

Naming conventions

• Avoid using lowercase letters l(L) , uppercase letters, O(o) or I(i) separate names as a variable to differentiate between numbers 1 and0
• Packages and modules use all lowercase names and try not to use underscores
• The class name uses CamelCase a naming style, and the inner class can start with an underscore;
  The contracted abbreviations are left as-is, for example, to use HTTPWriter insteadHttpWriter
• The function uses an underscore-delimited lowercase name,lowercase_with_underscores
• When the parameter name and the python reserved word conflict, you can add an underscore at the end and try not to use abbreviations or self-made words
• Constants are named with an underscore-delimited capitalization,UPPERCASE_WITH_UNDERSCORES
• Precompiled Regular Expressions:name_re

100Class FooBar:        foo_bar (  

Function and Method arguments:

• Class methods: As first cls parameter.
• Instance methods: As first self parameter.
• Lambdas for properties is the first parameter replaced x with, as in display_name = property(lambda x: x.real_name or x.username) .

Coding

• File using UTF-8 encoding
• File header Join #-*-coding:utf-8-*- logo

Python Code format specification