@echo off

REM This script launches the given Python script from the given directory

REM Chris Nyland

REM 2015-12-09

REM Last Updated: 2017-10-19

REM This script launches the given Python script taking into account several

REM situations. There are a total of three arguments that can be given.

REM The first is the full path to the directory where the script in question

REM resides. The second argument is the name of the script it self. The

REM third argument is optional and effects the way the script is launched.

REM Specifically there are two different ways to start the script in PDB

REM debugger mode and starting it in and IPython interactive session.

REM This script also searches for the existence of a virtual environment and

REM if found activates it and runs the script using the virtual environment.

REM The virtual environment is found by searching for a specified folder name

REM defined by the "np_virtualfolder" variable in the script below.

REM The Python installation to start the script with is determined by using the

REM Py Launcher program and the shebang line in the script file. If no

REM shebang line is present then the default Python installation found by

REM PyLauncher.

REM This will fail badly if the line endings are not Windows

REM Give the window a unique title

title PyLauncher Running %1 %2

REM Setup most of the variables that we need for the script

set np_virtualfolder=venv

set np_virtualscripts=%1\%np_virtualfolder%\Scripts\

set np_virtualactivate=%np_virtualscripts%activate.bat

set np_virtualdeactivate=%np_virtualscripts%deactivate.bat

set np_getexe=%~dp0np_getexecutable.txt

REM The pushd allows the script to deal with UNC paths however

REM if the batch script terminates abnormally then the drive letter

REM that was created by the script will remain.

pushd %1

REM Grab the first line of the script file

REM This will fail if the line endings are not windows

set /p firstline=<%2

REM If the virtual environment exists then activate it

REM echo %np_virtualactivate%

IF EXIST %np_virtualactivate% (

call %np_virtualactivate%

echo Virtual

)

REM If the first line is a shebang line which is identified as the first

REM two characters being "#!". Then write that line to a temp file else

REM wipe the temp file out since it is reused every time

IF "%firstline:~0,2%"=="#!" (

echo %firstline% > %np_getexe%

) ELSE (

break > %np_getexe%

)

REM Write code to the file that will print the path to the Python

REM executable used to stdout

(

echo import sys

echo print^(sys.executable^)

) >> %np_getexe%

REM Run the temp file using the PyLauncher and then save the output to the

REM variable np_pythonexecutable. Then get the directory in which the Python

REM executable resides.

for /f "delims=" %%i in ('py %np_getexe%') do set np_pythonexecutable="%%i"

for %%i in (%np_pythonexecutable%) do set np_pythondirectory=%%~dpi

REM This is setup for the IPython executable. I am doing it here because of

REM some nonsense about expanding variables that I honestly don't understand

REM but if I do this setup below in the if statements the variables won't get

REM set correctly. Basically what is happening here though is if this is a

REM virtual environment then the python.exe is in the Scripts folder with all

REM the other executables. So we don't need to add Scripts to path to get

REM to the IPython executable.

IF "%np_pythondirectory:~-8%"=="Scripts\" (

set np_pythonscriptspath=%np_pythondirectory%

) ELSE (

set np_pythonscriptspath=%np_pythondirectory%Scripts\

)

REM Set the path to the IPython executable and the error message if needed

set inp_pythonexecutable=%np_pythonscriptspath%ipython.exe

set ipythonerrormsg=IPython executable does not exist at %inp_pythonexecutable% running Python interactive instead

REM Print the Python version out to the screen

echo Running Python

REM echo %np_pythonexecutable%

%np_pythonexecutable% -c "import sys; print(sys.version)"

REM If the third argument is "pdb" then run the script under PDB debugger

REM mode. If the third argument is "ipython" then run the script under

REM a IPython interactive session with PDB mode enabled. Else finally

REM just run the script using the PyLauncher

IF "%3"=="pdb" (

%np_pythonexecutable% -m pdb %2

) ELSE IF "%3"=="ipython" (

IF EXIST "%inp_pythonexecutable%" (

"%inp_pythonexecutable%" -i --pdb %2

) ELSE (

echo %ipythonerrormsg%

%np_pythonexecutable% -i %2

)

) ELSE (

py -W once %2

)

REM Deactivate the virtual environment if it exists and then popd the

REM directory. After which we pause so that any error messages can be viewed.

IF EXIST %np_virtualdeactivate% call %np_virtualdeactivate%

popd

pause