How to use Pylint to standardize Python code style (from IBM)_python

This article provides a comprehensive introduction to the Python code analysis tool Pylint through a detailed theoretical introduction and easy-to-understand examples. I believe that readers will be able to easily apply Pylint to their own development projects after reading this

What is Pylint

Pylint is a Python code analysis tool that analyzes Python Errors in the code, looking for code that does not comply with coding style standards (the coding style used by Pylint by default is PEP 8, see Resources for specific information) and potentially problematic code. The latest version of Pylint is currently pylint-0.18.1.

• Pylint is a Python tool. In addition to the functions of ordinary code analysis tools, it provides more functions: such as checking the length of a line of code, whether the variable name meets the naming standards, Whether a declared interface is actually implemented, etc.

• One of the great benefits of Pylint is that it is highly configurable, highly customizable, and it is easy to write small plug-ins to add functionality.

• If you run Pylint twice, it will display the results of the current and last runs at the same time, so you can see whether the code quality has been improved.

• Pylint is currently integrated into the pydev plug-in of eclipse.

Pylint detailed introduction

Pylint installation

Pylint can be used for all Python versions higher than or equal to 2.2 and is compatible . The packages logilab-astng (version >= 0.14) and logilab-common (version >= 0.13) are required (see Resources for specific information). If the Python version is lower than 2.3, then it also requires the optik package (this article The following examples will not consider this case).

The download address of all packages used by Pylint

The latest package download of logilab-astng: http://www.logilab.org/856/

logilab-common’s latest package download: http://www.logilab.org/848/

optik’s package download: http://optik.sourceforge.net/

Pylint installation on Linux

2. Download the packages of Pylint, logilab-astng (version >= 0.14) and logilab-common (version >= 0.13), and use tar zxvf *.tar.gz to decompress these packages.
3. Enter the folders where logilab-astng, logilab-common and Pylint were extracted in order, and run the command Python setup.py install to install.
4. After the installation is complete, you can call Pylint through pylint [options] module_or_package.

Installation of Pylint on Windows

2. Use the decompression tool to decompress all packages.
3. Open the command line window, use cd to enter the unpacked folders of logilab-astng, logilab-common and Pylint in sequence, and run the command python setup.py install to install.
4. After the installation is completed, a Scripts folder will appear in the Python installation path, which contains some bat scripts, such as pylint.bat, etc.
5. In order to avoid entering the full path when calling pylint.bat, create a redirection file of pylint.bat in the Python installation directory. This is a plain text file pylint.bat, which contains pylint.bat. Actual path, such as: C:\Python26\Scripts\pylint.bat.
6. After the installation is complete, you can call Pylint through pylint [options] module_or_package.

Pylint calling

Use Pylint to check the code of a module module.py:

1. Enter the folder where the module is located and run
• pylint [options] module.py

  This method of calling will always work because the current working directory will be automatically added to the Python path.
  

2. Without entering the folder where the module is located, run
• pylint [options] directory/module.py

  This calling method is used when the following conditions are met It will work if the directory is a Python package (for example, contains an __init__.py file), or if the directory is added to the Python path. <br>

Use Pylint to check the code of a package:

1. Enter the folder where the package is located and run
• pylint [options ] pakage

  . This method of calling will always work because the current working directory will be automatically added to the Python path.
  

2. Without entering the folder where the package is located, run
• pylint [options] directory/ pakage

  . In this case, it can work when the following conditions are met: directory is added to the Python path. For example, on Linux, export PYTHONPATH=$PYTHONPATH: directory.

In addition, for machines with the tkinter package installed, you can use the command pylint-gui to open a simple GUI interface, enter the name of the module or package here (the rules are the same as the command line), and click Run. Pylint's output is displayed in the GUI.

Pylint’s common command line parameters

• -h,--help

  Display all help information.

• --generate-rcfile

  You can use pylint --generate-rcfile to generate an example configuration file. You can use redirection to save this configuration file for later use. You can also add other options in front so that the values ​​of these options are included in the generated configuration file. For example: pylint --persistent=n --generate-rcfile > pylint.conf. If you look at pylint.conf, you can see that persistent=no is no longer its default value of yes.

• --rcfile=

  Specify a configuration file. Put the configuration you use in the configuration file, which not only standardizes your own code, but also makes it easy to share these specifications with others.

• -i , --include-ids=

  Include the message id in the output, and then pass pylint --help- msg= to view the detailed information of this error so that you can specifically locate the error.

• ##-r , --reports=
  The default is y, which means that in addition to the source code analysis part, Pylint's output also Contains reporting section.

• --files-output=
  Output the message of each module/package to a file named pylint_module/package.[txt|html] In the file, if there is a report, it will be output to a file named pylint_global.[txt|html]. The default is to output to the screen and not to a file.

• -f , --output-format=
  Set the output format. The formats that can be selected are text, parseable, colorized, msvs (visual studio) and html. The default output format is text.

• --disable-msg=
  Disable messages with specified ids. For example, if the output contains the warning message W0402, if you do not want It appears in the output, you can use --disable-msg= W0402

Output of Pylint

import string 
 #!/usr/bin/env python 
 
 import xml.dom.minidom 
 
 xmlDom=xml.dom.minidom.parse("identity.xml") 
 organizations = xmlDom.getElementsByTagName('DW') 
 for org in organizations: 
  products = org.getElementsByTagName('linux') 
 for product in products: 
  print 'ID: ' + product.getAttribute('id') 
  print 'Name: ' + product.getAttribute('name') 
  print 'Word Count: ' + product.getAttribute('count')

<IBM> 
  <DW> 
    <linux id="100" name="python" count="3000" /> 
  </DW> 
</IBM>

#!/usr/bin/env python 
 
"""This script parse the content of a xml file"""
 
 import xml.dom.minidom 
 
 xmlDom=xml.dom.minidom.parse("identity.xml") 
 organizations = xmlDom.getElementsByTagName('DW') 
 for org in organizations: 
 products = org.getElementsByTagName('linux') 
 for product in products: 
  print 'ID: ' + product.getAttribute('id') 
  print 'Name: ' + product.getAttribute('name') 
  print 'Word Count: ' + product.getAttribute('count')

#!/usr/bin/env python 
 
"""This script parse the content of a xml file"""
 
 import xml.dom.minidom 
 
 xmldom = xml.dom.minidom.parse("identity.xml") 
 organizations = xmldom.getElementsByTagName('DW') 
 for org in organizations: 
 products = org.getElementsByTagName('linux') 
 for product in products: 
  print 'ID: ' + product.getAttribute('id') 
  print 'Name: ' + product.getAttribute('name') 
  print 'Word Count: ' + product.getAttribute('count')