Full support of Python 3 in GRASS GIS

Title:	Full support of Python 3 in GRASS GIS
Student Name:	Sanjeet Bhatti
Organization:	​OSGeo - Open Source Geospatial Foundation
Mentor Name:	Anna Petrášová and Luca Delucchi
GSoC proposal:	​View proposal
Link to code:	​Code Repository

Abstract

The current GRASS GIS version has partial support for Python 3. This project aims to update core GRASS components for Python 3 and update all the python modules, libraries and components like script package, python/ctypes, pygrass, temporal, wxGUI, etc. At the end of this project, GRASS GIS will be compatible with both the versions of python, i.e Python 2.7 and Python 3 with its GUI having support for wxPython 4.

Timeline

Time Period	Milestones
	Tasks	Status
April 23 - May 14 Community Bonding	Introduction to Community Create Wiki page Set up code repository Add links to community wiki pages Set up development environment Discussion with mentors about the libraries tests for the project Get familiar with the testing framework Update current tests of the python script library, adjust them to work with Python3 Get familiar with the overall working of GRASS GIS and understand Python dependencies in the system Read documentation Practice fixing bugs	Done
May 14 - May 20 Week 1	Dealing with Unicode & binary data (encoding and decoding). Setting up the foundation for porting the main libraries and components	Done
May 21 - May 27 Week 2	Porting script package module and its dependencies	Done
May 28 - June 3 Week 3	Porting other scripts and small libraries Write tests to check the consistency of libs subsequent to the changes
June 4 - June 10 Week 4	Finish pending work for this phase, if any. Doing some research on ctypesgen and pygrass Preparing and testing the changes for the evaluation
July 11 - July 15 Evaluation 1	Evaluation of work done in the previous phase Next phase discussions
June 11 - June 17 Week 5	Incorporate any changes, as necessary, from the discussions and feedback Work on Porting ctypes module
June 18 - June 24 Week 6	Porting pygrass module and its dependencies
June 25 - July 1 Week 7	Porting temporal module and its dependencies Porting remaining libs and their dependencies
July 2 - July 8 Week 8	Finish pending work for this phase, if any. Preparing and testing the changes for the evaluation
July 9 - July 13 Evaluation 2	Evaluation of work done in the previous phase Next phase discussions
July 9 - July 29 Week 9-11	Based on the feedback, make necessary changes Writing additional classes in wrap.py for updating wxGUI to be compatible with both wxPython 3 and 4. Finish porting to Python 3 Fixing all deprecated messages Testing the changes.
July 30 - August 5 Week 12	Preparing and testing all the changes Writing documentation for the final evaluation
August 6 - August 14 Evaluation 3 (Final)	Final code submission Evaluation of final submission

Community Bonding Period Report

During the Community Bonding Period I performed the following activities:

Introduction to Community
I wrote an introductory email to the SoC mailing list and grass-dev mailing list and gave a description about my project and shared my wiki page, public repository, and project proposal links.

Create Wiki page
I requested the write access to setup a project wiki page. Then, I created my wiki page detailing the project description, containing link to my GSoC application, a detailed timeline, link to my public repository where all my commits and progress can be followed.

Set up code repository
I have setup my code repository on github for tracking the applied changesets.

Set up development environment
I setup my development environment (Ubuntu 18.04) for two Python versions (Python 2.7.x and Python 3.6.x) for which I am using virtual environments. This was done because I need to make sure that when I update any code it should be compatible with both the versions.

Add links to community wiki pages
I added my project links to the OSGeo's Google Summer of Code 2018 Accepted students wiki page and trac wiki page: ​https://wiki.osgeo.org/wiki/Google_Summer_of_Code_2018_Accepted and ​https://trac.osgeo.org/grass/wiki/GSoC.

Discussion with mentors about the libraries tests for the project
I got in touch with my mentors to discuss the right approach to test the code and submit files. We discussed about the python libraries and their testsuites, starting with Python script library.

Get familiar with the testing framework
I followed the wiki page to get familiar with the testing framework(​https://grasswiki.osgeo.org/wiki/GRASS_and_Python). I also followed the grass Python Scripting tutorials from this link: ​https://github.com/wenzeslaus/python-grass-addon

Update current tests of the python script library, adjust them to work with Python3
I updated the code in the python script library to make it work on Python3 and submitted the patch files for those. I used the standard North Carolina dataset that uses the basic version of the dataset. (https://grass.osgeo.org/download/sample-data/) I have looked through the summary reports for the current tests of GRASS which is going to be useful when I will update tests for the libraries in the system. (​http://fatra.cnr.ncsu.edu/grassgistests/summary_report/)

Get familiar with the overall working of GRASS GIS and understand Python dependencies in the system
I went through the GRASS wiki pages to get familiar with the working of the system (https://grass.osgeo.org/grass75/manuals/libpython/) and looked through the source code. Also, I found the code dependencies that I will be working with throughout the coding period.

Read documentation
I read some documentation related to GSoC guidelines about working throughout the GSoC period. I also read GRASS GIS Python library documentation: (https://grass.osgeo.org/grass75/manuals/libpython/)

Practice fixing bugs
I wrote a bug fix related to wxPython(​https://trac.osgeo.org/grass/ticket/3510) during Pre-bonding period and submitted the patch file.

Weekly reports

Week 1

What did I complete this week?

• Updated the script for redundant lines in the patch submitted for utils.py
• Tested the patches on Python versions 2.7.x, 3.5.x and 3.6.x
• Read and understood the main differences about Strings, Unicode strings and Byte strings in Python 2 and 3 versions. Wrote some brief differences for quick reference(​https://docs.google.com/document/d/18Tvl0vpTSwOfO4xGKXpAo-h6o6WAAZmHX8neYIsHTtA)
• Read python's package futurize's documentation for Py2 to Py3 conversion
• Updated source code in python lib files (uncommitted, still testing)

What am I going to achieve for next week?

• Finish porting 'script' library to support Python3
• Test the changes for both the versions
• Implement any tests required for testing

Is there any blocking issue?

Not at the moment.