Google and pythongoogle

Google and pythongoogle

Mark the website at the beginning: goole Official Website

Programmers in any language compile code that complies with the specifications, which is the first step in their programming career.

I. semicolon

Do not add points at the end of a line, or use semicolons to place the two commands on the same line.

2. Line Length

Each line cannot exceed 80 characters

Exceptions:

1. Long import module statement
2. URL in the comment

Do not use a backslash to connect rows.

Python implicitly concatenates parentheses, braces, and rows in curly brackets. You can use this feature. If necessary, you can add an additional pair of parentheses to the outer side of the expression.

Yes: foo_bar(self, width, height, color='black', design=None, x='foo',             emphasis=None, highlight=0)     if (width == 0 and height == 0 and         color == 'red' and emphasis == 'strong'):

If a text string cannot be placed in one row, you can use parentheses to implement implicit row join.

x = ('This will build a very long long '     'long long long long long long string')

If necessary, place the long URL on a line.

Yes: # See details at # http://www.example.com/us/developer/documentation/api/content/v2.0/csv_file_name_extension_full_specification.html

No:  # See details at     # http://www.example.com/us/developer/documentation/api/content/\     # v2.0/csv_file_name_extension_full_specification.html

Brackets

We prefer to use brackets without abuse.

Do not use parentheses in the return statement or condition statement unless it is used to implement row join. However, it is acceptable to use parentheses on both sides of the tuples.

Iv. indent

Use four spaces to indent the code

Do not use tab, or mix tab and space.

For row join, you should either vertically align the elements of the line feed (see the example of the line length Section), or use a 4-space hanging indent (at this time, the first line should not have a parameter):

5. Empty rows

Two rows are empty between top-level definitions, and one row is empty between method definitions.

• There are two blank rows between top-level definitions, such as functions or class definitions.
• Method definition. A row should be blank between the class definition and the first method. In a function or method, if you think it is appropriate, leave a row empty.

6. Space

Use spaces on both sides of punctuation according to standard typographical specifications

7. Shebang

Most. py files do not need to use #! Start as a file. According to PEP-394, the main file of the program should start #! /Usr/bin/python2 or #! Start with/usr/bin/python3.

(Note: in computer science, Shebang (also known as Hashbang) is a string line consisting of a well number and an exclamation point (#!), It appears in the first two characters of the first line of the text file. when Shebang exists in the file, the program loader of the Unix-like operating system will analyze the Shebang content, use the content as the interpreter instruction, and call the instruction, the file path containing Shebang is used as the parameter of the interpreter. for example, the command #! Files starting with/bin/sh will actually call the/bin/sh program during execution .)

#! It is first used to help the kernel find the Python interpreter, but will be ignored when the module is imported. Therefore, it is necessary to add # To the file that is directly executed #!.

8. Notes

Make sure that the correct style is used for module, function, method, and in-line comments.

Block comment and line comment

The most important thing to note is the technical part of the code. if you need to explain it during the next code review, you should write comments to it now. for complex operations, you should write several lines of comments before the operation starts. for codes that are not clear at a glance, add comments at the end of the line.

To improve readability, comments should leave at least two spaces in the code.

On the other hand, never describe the Code. If the person who reads the code knows Python better than you, he just doesn't know what your code is going to do.

IX. Category

If a class does not inherit from other classes, it will explicitly inherit from the object. The same is true for nested classes.

Inherited fromobjectThis is to make properties work normally and protect your code from a special potential incompatibility of PEP-3000. this also defines some special methods that implement the default semantics of objects, including

__new__, __init__, __delattr__, __getattribute__, __setattr__, __hash__, __repr__, and __str__

10. String

Even if the parameters are strings, use the % operator or the formatting method to format the strings. However, they cannot be generalized. You need to determine between + and %.

Avoid using the + and + = operators in the loop to accumulate strings. because the string is immutable, this will create unnecessary temporary objects and lead to quadratic instead of linear runtime. as an alternative, you can add each substring to the list and then use.joinConnection list. (You can also write each substring to onecStringIO.StringIOCache .)

11. Files and sockets

Close the file explicitly at the end of the file and sockets.

12. TODO comments

Use TODO annotations for temporary code. It is a short-term solution. It is not perfect, but it is good enough.

13. Import format

Each import must have an exclusive row.

The import should always be placed at the top of the file, after the module comments and document strings, before the global variables and constants of the module, the import should be grouped from the most general to the least General Order:

1. Standard Library Import
2. Third-party library Import
3. Application Specified Import

In each group, the complete package path of each module should be sorted alphabetically, regardless of case.

Statement

Generally, each statement should have an exclusive row.

However, if the test results and test statements are placed in one row, you can also put them in the same row.

If it is an if statement, this can be done only when there is no else. In particular, nevertry/exceptThis is because try and try cannot be placed in the same row.

15. Access Control

In Python, you should replace trivial and unimportant access functions with public variables to avoid additional function call overhead. when adding more functions, you can use properties to maintain syntax consistency. (Translator's note: Object-oriented programmers who pay attention to encapsulation may be disgusted with this because they have been educated: All member variables must be private! Actually, it is a little troublesome. Try to accept the Pythonic philosophy)

16th. Name

module_name, package_name, ClassName, method_name, ExceptionName, function_name, GLOBAL_VAR_NAME, instance_var_name, function_parameter_name, local_var_name.

Names to be avoided

 
 

  
  
Single character name, except counters and iterators.
  
  
Hyphens (-) in the package/Module name (-)
  
  
Name starting with and ending with a double underline (retained by Python, for example, _ init __)
 
 

Naming Conventions

 
 

  
  
The so-called "Internal (Internal)" indicates that only the module is available, or, is protected or private within the class.
  
  
Start with a single underscore (_) to indicate that the module variable or function is protected (not included when import * from is used ).
  
  
Instance variables or methods starting with double underscores (_) indicate private in the class.
  
  
Place related classes and top-level functions in the same module. Unlike Java, there is no need to restrict one class and one module.
  
  
The class name should start with an upper-case letter (for example, CapWords, or Pascal style), but the module name should be underlined in lower case (for example, lower_with_under.py ). although many existing modules use CapWords. however, this is not encouraged because the module name happens to be the same as the class name.
 
 

Specifications recommended by Guido, father of Python

Type	Public	Internal
Modules	Lower_with_under	_ Lower_with_under
Packages	Lower_with_under
Classes	CapWords	_ CapWords
Exceptions	CapWords
Functions	Lower_with_under ()	_ Lower_with_under ()
Global/Class Constants	CAPS_WITH_UNDER	_ CAPS_WITH_UNDER
Global/Class Variables	Lower_with_under	_ Lower_with_under
Instance Variables	Lower_with_under	_ Lower_with_under (protected) or _ lower_with_under (private)
Method Names	Lower_with_under ()	_ Lower_with_under () (protected) or _ lower_with_under () (private)
Function/Method Parameters	Lower_with_under
Local Variables	Lower_with_under

17. Main

Even a file intended to be used as a script can be imported. in addition, a simple import should not cause the main function of the script to be executed, which is a side effect. the main function should be placed in a main () function.