# Cling - The LLVM-based C++ Interpreter

- Institution: CERN
- Department: Conferences
- Speaker: Vasil Georgiev Vasilev
- Year: 2012
- Language: English
- Subjects: Physics, Computer science, Earth and environment
- Source: [CERN](https://videos.cern.ch/record/3009558)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Tweens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

Cling (http://cern.ch/cling) is a C++ interpreter, built on top of clang (http://clang.llvm.org) and LLVM (http://llvm.org). Like its predecessor CINT, cling offers an interactive, terminal-like prompt. It enables exploratory programming with rapid edit / run cycles.

The ROOT team has more than 15 years of experience with C++ interpreters, and this has been fully exploited in the design of cling. However, matching the concepts of an interpreter to a compiler library is a non-trivial task; we will explain how this is done for cling, and how we managed to implement cling as a small (10,000 lines of code) extension to the clang and llvm libraries.

The resulting features clearly show the advantages of basing an interpreter on a compiler. Cling uses clang's praised concise and easy to understand diagnostics. Building an interpreter on top of a compiler library makes the transition between interpreted and compiled code much easier and smoother. We will present the design, e.g. how cling treats the C++ extensions that used to be available in CINT. We will also present the new features, e.g. how C++11 will come to cling, and how dictionaries will be simplified due to cling. We describe the state of cling's integration in the ROOT Framework..

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## Lectures

1. [Cling - The LLVM-based C++ Interpreter](https://invisiblenetwork.ai/learn/cern/3009558/bde5c8061742), 25 min (CERN's player)