2. Interactivity in C++ with Cling

Interactive programming is a programming approach that allows developers to

change and modify the program as it runs. The final result is a program that actively responds to a developers’ intuitions, allowing them to make changes in their code, and to see the result of these changes without interrupting the running program. Interactive programming gives programmers the freedom to explore different scenarios while developing software, writing one expression at a time, figuring out what to do next at each step, and enabling them to quickly identify and fix bugs whenever they arise. As an example, the High-Energy Physics community includes professionals with a variety of backgrounds, including physicists, nuclear engineers, and software engineers. Cling allows for interactive data analysis in ROOT by giving researchers a way to prototype their C++ code, allowing them to tailor it to the particular scope of the analysis they want to pursue on a particular set of data before being added to the main framework.

Interpreted language is a way to achieve interactive programming. In

statically compiled language, all source code is converted into native machine code and then executed by the processor before being run. An interpreted language instead runs through source programs line by line, taking an executable segment of source code, turning it into machine code, and then executing it. With this approach, when a change is made by the programmer, the interpreter will convey it without the need for the entire source code to be manually compiled. Interpreted languages are flexible, and offer features like dynamic typing and smaller program size.

Cling is not an interpreter, it is a Just-In-Time (JIT) compiler that feels

like an interpreter, and allows C++, a language designed to be compiled, to be interpreted. When using Cling, the programmer benefits from both the power of C++ language, such as high-performance, robustness, fastness, efficiency, versatility, and the capability of an interpreter, which allows for interactive exploration and on-the-fly inspection of the source-code.