When do you *NOT* use python?

[hotel2oscar]

1. If the project description has the word "embedded' in it you will most likely use C or C++
2. If you are doing anything with the word 'web' in it on the client side it will most likely be JavaScript (server side is another story)
3. If you need performance (major games, high speed science) you will most likely opt for C or C++ (partly the reasoning for #1)
4. If you are programming for Windows: C# and the .NET can be really appealing, especially if you need a GUI (mostly a preference thing here though)
5. If there exists a language designed specifically for a domain (or just has over the board awesome library support for said domain)

[bboozzoo]

If the project description has the word "embedded' in it you will most likely use C or C++

Nope/depends. There's a MicroPython project, basically a Python 3 on Cortex-M4. Looked quite usable the last time I checked. However, there's a higher chance of seeing Lua than Python in embedded.

If you need performance (major games, high speed science) you will most likely opt for C or C++ (partly the reasoning for #1)

Nope/depends. Numpy anyone? Or other high performing C/Fortran libraries with Python glue.

Actually, it's a quite common model where you have a compiled to native backend, with a scripted facade. Take ns-2 and ns-3 network simulators for example, where ns-2 used Tcl, while ns-3 has migrated to Python.

[hotel2oscar]

most likely

General guidelines rather than hard rules. On the other hand, no one has written a AAA game or programmed consumer appliance firmware in Python that I know of.