nvda

528d5708 - Py3.8: Transparently use a Python virtual environment under the hood (#12075)

Py3.8: Transparently use a Python virtual environment under the hood (#12075) A Python virtual environment is now used transparently by the NVDA build system, and all Python dependencies are installed into this environment using pip. From a developer's perspective using the NVDA build system, there is no need to worry about the Python virtual environment behind the scenes, nor should you create and or activate one manually. All NVDA build system commands will handle this transparently. * To build NVDA, SCons should continue to be used in the usual way. E.g. executing scons.bat in the root of the repository. Running py -m SCons is no longer supported, and scons.py has also been removed. * To run NVDA from source, rather than executing source/nvda.pyw directly, the developer should now use runnvda.bat in the root of the repository. If you do try to execute source/nva.pyw, a message box will alert you this is no longer supported. * To perform unit tests, execute rununittests.bat [<extra unittest discover options>] * To perform system tests: execute runsystemtests.bat [<extra robot options>] * To perform linting, execute runlint.bat <base branch> Behind the scenes, the above batch files (scons, runnvda, rununittests, runsystemtests and runlint) ensure that the Python virtual environment is created and up to date, activates the environment, runs the command and then deactivates. All transparently. A developer should not have to know about the Python virtual environment at all. The first time one of these commands are run, the virtual environment will be created, and all required Python dependencies will be installed with pip. You can see the entire list of packages and their exact versions that pip will use, in requirements.txt in the root of the repository. venvUtils/ensureVenv.py contains the logic to check for, create and update the virtual environment. If a previous virtual environment exists but has a miss-matching Python version or pip package requirements have changed, The virtual environment is recreated with the updated version of Python and packages. If a virtual environment is found but does not seem to be ours, the user is asked if it should be overwritten or not. This script also detects if it is being run from an existing 3rd party Python virtual environment and aborts if so. thus, it is impossible to execute SCons or NVDA from source within another Python virtual environment. venvUtils/ensureAndActivate.bat can be used to ensure the virtual environment exists and is up to date, and then activates it in the current shell, ready for other commands to be executed in the context of NVDA's build system Python virtual environment. this would never normally be executed by itself, though appVeyor uses it at the beginning of its execution and leaves the environment active for the remainder of its execution. venvUtils/venvCmd.bat is a script that runs a single command within the context of the NVDA build system Python virtual environment. It ensures and activates the environment, executes the command, and then deactivates the environment. this script is what all the high-level batch files use internally. SConstruct, and source/nvda.pyw both contain logic that detects the NVDA build system Python virtual environment, and abort if it is not active. As this PR is specific for Python 3.8, it also upgrades the following Python dependencies: • wxPython to 4.1.1 • pySerial to 3.5 • py2exe to 0.10.1.0