The C++ language supports several programming paradigms including object-oriented programming. Speed is its main advantage, as C++ is not interpreted but compiled. It is also multi-platform, as long as you use the C++ STL.
Python is a free, portable, dynamic, and extensible language which enables (but does not require) modular, object-oriented programming. It is particularly suitable for scientific computing and imaging. In such fields Python is not used to write algorithms, but rather to combine and quickly implement computing libraries written in a compiled language such as C, C++, Fortran or Ada.
Delphi is both an object programming language and a development environment. It implements an object version of Pascal language. Originally developed by Borland, it was bought by Embarcadero in 2011. We mainly use Delphi to carry out maintenance on legacy systems which we are gradually porting to C++/QT environments.