The cling C++ interpreter
The main repository is at https://github.com/root-project/cling
Cling is an interactive C++ interpreter, built on top of Clang and LLVM compiler
infrastructure. Cling implements the read-eval-print loop
(REPL)
concept, in order to leverage rapid application development. Implemented as a
small extension to LLVM and Clang, the interpreter reuses their strengths such
as the praised concise and expressive compiler diagnostics.
See also cling’s web page.
Please note that some of the resources are rather old and most of the stated
limitations are outdated.
See our release notes to find what’s new.
Our nightly binary snapshots are currently unavailable.
See also the instructions on the webpage.
If Clang and LLVM (cling-latest version) are not installed, you need to build them first:
git clone https://github.com/root-project/llvm-project.gitcd llvm-projectgit checkout cling-latestcd ..mkdir llvm-build && cd llvm-buildcmake -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_TARGETS_TO_BUILD="host;NVPTX" -DCMAKE_BUILD_TYPE=Release ./llvm-project/llvmcmake --build .
Once Clang and LLVM (cling-latest version) are installed, you can build Cling. If they are already installed, you can skip the previous step and proceed with the following:
Note: Ensure you are outside the llvm-project and llvm-build directories before proceeding, as LLVM, Clang, and Cling do not allow building inside the source directory.
git clone https://github.com/root-project/cling.gitmkdir cling-build && cd cling-buildcmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH="The root of your LLVM build directory" -DLLVM_DIR="The directory containing LLVM's CMake modules" ../clingcmake --build .
Example CMake command:
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=../llvm-build -DLLVM_DIR=../llvm-build/lib/cmake/llvm ../cling
If Clang and LLVM are not installed, you can build them together with Cling:
git clone https://github.com/root-project/llvm-project.gitcd llvm-projectgit checkout cling-latestcd ..git clone https://github.com/root-project/cling.gitmkdir cling-build && cd cling-buildcmake -DLLVM_EXTERNAL_PROJECTS=cling -DLLVM_EXTERNAL_CLING_SOURCE_DIR=../cling/ -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_TARGETS_TO_BUILD="host;NVPTX" -DCMAKE_BUILD_TYPE=Release ../llvm-project/llvmcmake --build . --target clang cling
To enable support for cling in Jupyter notebooks, after building cling, run:
cmake --build . --target libclingJupyter
Assuming we’re in the build folder.
If Cling is built as a standalone project, you need to specify the include directory for headers:
./bin/cling -I"../cling/include" '#include <stdio.h>' 'printf("Hello World!\n");'
If build Cling as part of LLVM:
./bin/cling '#include <stdio.h>' 'printf("Hello World!\n");'
To get started run:
./bin/cling --help
or
./bin/cling[cling]$ .help
Cling comes with a Jupyter kernel. After building cling,
install Jupyter and cling’s kernel by following the README.md in
tools/Jupyter. Make sure cling is in your PATH when you start jupyter!
% Peer-Reviewed Publication % % 19th International Conference on Computing in High Energy and Nuclear Physics (CHEP) % 21-25 May, 2012, New York, USA % @inproceedings{Cling, author = {Vassilev,V. and Canal,Ph. and Naumann,A. and Moneta,L. and Russo,P.}, title = {{Cling} -- The New Interactive Interpreter for {ROOT} 6}}, journal = {Journal of Physics: Conference Series}, year = 2012, month = {dec}, volume = {396}, number = {5}, pages = {052071}, doi = {10.1088/1742-6596/396/5/052071}, url = {https://iopscience.iop.org/article/10.1088/1742-6596/396/5/052071/pdf}, publisher = {{IOP} Publishing} }
Cling’s latest doxygen documentation
Every contribution is considered a donation and its copyright and any other
related rights become exclusive ownership of the person who merged the code or
in any other case the main developers of the “Cling Project”.
We warmly welcome external contributions to the Cling! By providing code,
you agree to transfer your copyright on the code to the “Cling project”.
Of course you will be duly credited and your name will appear on the
contributors page, the release notes, and in the CREDITS file
shipped with every binary and source distribution. The copyright transfer is
necessary for us to be able to effectively defend the project in case of
litigation.
Please see our LICENSE.
Our release steps to follow when cutting a new release:
~dev suffix from VERSIONgit tag -a v0.x -m "Tagging release v0.x"cling-patches of clang.git:git tag -a cling-v0.x -m "Tagging clang for cling v0.x"~dev.