Instructions.txt

Up to now I've been using wscript.exe that launches a .vbs script which acts as a buffer for launching a .cmd (.bat) file. The latter contains the path to executable along with arguments. IIRC launching the .cmd file directly caused some problems.

But this solution is too convoluted, and that is why I'd like to simplify it and run Python with multiple arguments directly from Launch App(*).

Try this
http://www.digitalfossils.com/Download/NVil-Dec-20a-17.rar

Okay, the file not found error is gone, but now NVil treats Hython.exe and the .py script, which I want to pass as an argument to, as two separate executables. It launches both as separate applications. First Houdini's Python interpreter (Hython) shows up, and then Windows asks me which program should be used to launch my .py file.

That sounds too complicated.

Try this
http://www.digitalfossils.com/Download/NVil-Sep-27-16.rar

Instead of sending window message, you can send a text file "NVil Message_In.txt" with this content "Execute External Instruction File" to "%APPDATA%\DigitalFossils\NVil". Make sure 3DC Applink is enabled.

BTW, NVil Message_In.txt works really well.

Okay, the file not found error is gone, but now NVil treats Hython.exe and the .py script, which I want to pass as an argument to, as two separate executables. It launches both as separate applications. First Houdini's Python interpreter (Hython) shows up, and then Windows asks me which program should be used to launch my .py file.

Try any of these

"C:\Program Files\Side Effects Software\Houdini 16.5\bin\hython.exe"; "c:\users\myprofile\documents\houdini16.5\python27libs\myscript.py"

C:\Program Files\Side Effects Software\Houdini 16.5\bin\hython.exe; c:\users\myprofile\documents\houdini16.5\python27libs\myscript.py

Okay, the file not found error is gone, but now NVil treats Hython.exe and the .py script, which I want to pass as an argument to, as two separate executables. It launches both as separate applications. First Houdini's Python interpreter (Hython) shows up, and then Windows asks me which program should be used to launch my .py file.

Try any of these
"C:\Program Files\Side Effects Software\Houdini 16.5\bin\hython.exe"; "c:\users\myprofile\documents\houdini16.5\python27libs\myscript.py"
(...)

Semicolon did the trick. Thanks!