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	Done
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	Done
July 11 - July 15 Evaluation 1	Evaluation of work done in the previous phase Next phase discussions	Done
June 11 - June 17 Week 5	Incorporate any changes, as necessary, from the discussions and feedback Work on Porting ctypes module	Done
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 the 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.

Week 2

What did I complete this week?

• Updated the encode and decode function in utils.py to accept the encoding type
• Ported functions from 'Script' library to deal with unicode/bytes (​https://gist.github.com/sanjeetbhatti/6714dff40b8a0a6d30df25ce9e4faa20)
• Tested the changes by running tests (testsuites)
• Tested against the python-grass-addon scripts available from here (​https://github.com/wenzeslaus/python-grass-addon)

What am I going to achieve for the next week?

• Write more tests for script library to test the changes
• Look into the issue of running scripts for Python 3.5 and Python 3.6 (some tests fail on either of the versions)
• Port other small libraries and scripts

Is there any blocking issue?

Not at the moment.

Week 3

What did I complete this week?

• Wrote new tests for 'Script' library (​https://github.com/sanjeetbhatti/FullSupportPython3/tree/master/grass_trunk/lib-python-script)
• Made changes to the existing source files according to the failing tests (​https://docs.google.com/spreadsheets/d/1eAIJtegNWSbBscFChhQzMTl0vmbGPjmrW_013hSw9bI/#gid=0)
• Updated scripts in 'trunk/Scripts' (​https://github.com/sanjeetbhatti/FullSupportPython3/tree/master/grass_trunk/scripts)
• Created a spreadsheet to keep track of the status for all trunk/scripts (​https://docs.google.com/spreadsheets/d/1eAIJtegNWSbBscFChhQzMTl0vmbGPjmrW_013hSw9bI/#gid=278198865)
• Tested the changes with Python versions 2.7, 3.5 and 3.6
• Cleaned the patches according to the pep8 guidelines and pushed those patches to the repository

What am I going to achieve for the next week?

• After discussion and feedback from the mentors, finish pending work
• Look into ctypes and pygrass libraries
• Discuss with mentors about possible solutions for ctypes
• Test all the changes done for the evaluation period

Is there any blocking issue?

Not at the moment.

Week 4

What did I complete this week?

• Wrote new tests for 'trunk/scripts' according to the priority (​https://github.com/sanjeetbhatti/FullSupportPython3/tree/master/grass_trunk/scripts)
• Updated some files in 'gunittest' library pertaining to the 'trunk/scripts' (​https://github.com/sanjeetbhatti/FullSupportPython3/tree/master/grass_trunk/lib-python-gunittest)
• Looked into different forks of ctypes library
• Got the fork with latest changes, tried compiling with Py3
• Tested the changes done, updated the repository (​https://github.com/sanjeetbhatti/FullSupportPython3/)

What am I going to achieve for the next week?

• Submit the first evaluation
• Work on any changes necessary after discussion and feedback from the mentors
• Start working on porting the ctypes library

Is there any blocking issue?

Not at the moment.

Week 5

What did I complete this week?

• Updated tests for 'trunk/scripts' as per the feedback (​https://github.com/sanjeetbhatti/FullSupportPython3/tree/master/grass_trunk/scripts)
• Made changes in the 'ctypes' library to make it compile with Py3 (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-ctypes/patch_ctypes.diff)
• Added another patch for 'ctypes' to include the changes from the latest fork of ctypes (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-ctypes/patch_ctypes_changes_from_fork.diff)
• Tested the changes with Python versions 2.7, 3.5 and 3.6

What am I going to achieve for the next week?

• Work on 'pygrass' module
• Compare changes of ctypes compiled version among all 3 versions with and without changes
• Write new tests for some of the remaining scripts in 'trunk/scripts'

Is there any blocking issue?

Not at the moment.

Week 6

What did I complete this week?

• Fixed few issues and updated ctypes (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-ctypes/patch_ctypes_changes_from_fork.diff)
• Worked on 'Pygrass' library to make it work with the updated ctypes (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-pygrass/patch_pygrass.diff)
• Updated tests in 'pygrass' library

What am I going to achieve for the next week?

• Continue working on 'pygrass' module
• Work on 'temporal' library
• Fix pending issues in pygrass

Is there any blocking issue?

Not at the moment.

Week 7

What did I complete this week?

• Updated ctypes to deal with bytes(​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-ctypes/patch_ctypes_changes_from_fork.diff)
• Worked on 'temporal' library(​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-temporal/patch_temporal.diff), a lot of errors were encountered
• Looked into issues for 'pygrass' testsuites which were failing too
• Created a spreadsheet(​https://docs.google.com/spreadsheets/d/1eAIJtegNWSbBscFChhQzMTl0vmbGPjmrW_013hSw9bI/edit#gid=408919374) detailing errors and information regarding the temporal testsuites
• Also, updated the pygrass testsuite details on spreadsheet(​https://docs.google.com/spreadsheets/d/1eAIJtegNWSbBscFChhQzMTl0vmbGPjmrW_013hSw9bI/edit#gid=587128881)

What am I going to achieve for the next week?

• Start exploring GUI library, starting with mapdisp and imgr
• Continue working on fixing ctypes module
• Continue working on 'temporal' library

Is there any blocking issue?

Ctypes are not fully compatible with the Python3 even if they are compiling without any issues. Discussed with mentors about the next steps and how to deal with ctypes. Will discuss more about the upcoming milestones and how ctypes handling is to be done so as not to interfere too much with the pending work.

Week 8

What did I complete this week?

• Updated 'pygrass' library (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-pygrass/patch_pygrass.diff) fixed failing errors
• Updated 'pydispatch' to deal with dict iterator (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-pydispatch/patch_pydispatch.diff)
• Fixed 'ctypes' patch (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-ctypes/patch_ctypes_changes_from_fork.diff), was failing to apply
• Fixed import issues in GUI library (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/gui/patch_gui.diff)
• Fixed gconsole, goutput and gcmd errors to run the wxpython4 on Py3
• Updated all dict iterators (keys, values, items) in GUI library

What am I going to achieve for the next week?

• Fix deprecated code in GUI library
• Keep working on ctypes-pygrass-temporal libraries
• Write tests for trunk/scripts

Is there any blocking issue?

Not at the moment.

Week 9

What did I complete this week?

• Fixed 'temporal' library's connection issue (t.connect) (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/lib-python-temporal/patch_temporal.diff)
• Tested the code with temporal t.connect tests
• Fixed code for relative paths
• Fixed g.gui.animation part of gui (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/gui/patch_gui.diff)
• Wrote two new tests for trunk/scripts (testing pending)

What am I going to achieve for the next week?

• Fix deprecated code in GUI library
• Fix other gui command files
• Keep working on temporal library
• Test all the reamining files in temporal testsuite

Is there any blocking issue?

Not at the moment.

Week 10

What did I complete this week?

• Replaced deprecated code warnings for set-tooltip (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/gui/patch_gui.diff)
• Fixed psmap issue for map
• Created new wrapper classes for widgets
• Fixed animation and mapswipe events binding deprecation warnings
• Fixed 'cmp' function calls, created custom function to deal with all instances

What am I going to achieve for the next week?

• Replace remaining code deprecated warnings in GUI library
• Fix remaining gui command files
• Work on forms.py to fix string errors
• Replace all instances of old wx.* code with wrapper classes where suitable

Is there any blocking issue?

Not at the moment.

Week 11

What did I complete this week?

• Replaced instances of old wx.* code with wrapper classes where suitable (​https://github.com/sanjeetbhatti/FullSupportPython3/blob/master/grass_trunk/gui/patch_gui.diff)
• Fixed forms.py string errors
• Added cmp function in utils
• Fixed remaining gui command files
• Decoded strings where necessary in base.py
• Added encoding in gmcd before hashing

What am I going to achieve for the next week?

• Fix assertion errors
• Fix remaining warnings in GUI library
• Do testing for GUI
• Prepare for evaluation, prepare deliverables

Is there any blocking issue?

Not at the moment.