Merge d5a3ef2 into 5fbe05d

michaelDCurran · web-flow · commit a8ae841ae1db · 2021-03-18T08:55:46.000+10:00
diff --git a/venvUtils/ensureAndActivate.bat b/venvUtils/ensureAndActivate.bat
@@ -1,9 +1,28 @@
 @echo off
 rem this script ensures the NVDA build system Python virtual environment is created and up to date,
 rem and then activates it.
-rem this script should be used only in the case where many commands will be executed within the environment and the shell will be eventually thrown away. 
-rem E.g. an Appveyor build.
+rem This is an internal script and should not be used directly.
+
+rem Ensure the environment is created and up to date
 py -3.8-32 "%~dp0\ensureVenv.py"
 if ERRORLEVEL 1 goto :EOF
-call "%~dp0\..\.venv\scripts\activate.bat"
+
+rem Set the necessary environment variables to have Python use this virtual environment.
+rem This should set all the necessary environment variables that the standard .venv\scripts\activate.bat does
+rem Except that we set VIRTUAL_ENV to a path relative to this script,
+rem rather than it being hard-coded to where the virtual environment was first created. 
+
+rem unset the PYTHONHOME variable so as to ensure that Python does not use a customized Python standard library. 
+set PYTHONHOME=
+rem set the VIRTUAL_ENV variable instructing Python to use a virtual environment
+rem py.exe will honor VIRTUAL_ENV and launch the python.exe that it finds in %VIRTUAL_ENV%\scripts.
+rem %VIRTUAL_ENV%\scripts\python.exe will find pyvenv.cfg in its parent directory,
+rem which is actually what then causes Python to use the site-packages found in this virtual environment.
+set VIRTUAL_ENV=%~dp0..\.venv
+rem Add the virtual environment's scripts directory to the path
+set PATH=%VIRTUAL_ENV%\scripts;%PATH%
+rem Set an NVDA-specific variable to identify this official NVDA virtual environment from other 3rd party ones
 set NVDA_VENV=%VIRTUAL_ENV%
+rem mention the environment in the prompt to make it obbvious it is active
+rem just in case this script is executed outside of a local block and not cleaned up.
+set PROMPT=[NVDA Venv] %PROMPT%
diff --git a/venvUtils/venvCmd.bat b/venvUtils/venvCmd.bat
@@ -16,12 +16,14 @@ if "%VIRTUAL_ENV%" NEQ "" (
 	goto :EOF
 )
 
+rem call setlocal to make sure that any environment variable changes made by activating the virtual environment
+rem can be completely undone when endlocal is called or this script exits.
 setlocal
 echo Ensuring NVDA Python virtual environment
 call "%~dp0\ensureAndActivate.bat"
 if ERRORLEVEL 1 goto :EOF
 echo call %*
 call %*
+rem the virtual environment will now be deactivated as endlocal will be reached.
 echo Deactivating NVDA Python virtual environment
-call "%~dp0\..\.venv\scripts\deactivate.bat"
 endlocal
