Introducing cpp4r: A C++ Interface for R’s C Interface
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cpp4r helps you to interact with R objects using C++ code. It is a fork of the cpp11 package with identical syntax and similar goals.
- Code: https://github.com/pachadotdev/cpp4r.
- Documentation: https://cpp4r.org/.
cpp4r can be used as a replacement for cpp11 in existing or new packages. Think of cpp11 and cpp4r as MySQL and MariaDB: they are almost identical, but cpp4r has some extra features.
After discussing some pull requests with Hadley Wickham from Posit, it was mentioned that I should create my own fork to add the following features:
- Convert ordered and unordered C++ maps to R lists.
- Roxygen support on C++ side.
- Allow
dimnamesatribute with matrices on C++ side. - Support nullable
external_ptr<>. - Use values added to a vector with
push_back()immediately. - Support bidirectional passing of complex numbers/vectors.
- Provide flexibility with data types (e.g., cpp4r’s
as_integers()andas_doubles()accept logical inputs while cpp11’s do not). - Some internal optimizations for better speed (e.g., https://github.com/r-lib/cpp11/pull/463 and https://github.com/r-lib/cpp11/pull/430).
Using cpp4r in a package
To add cpp4r to an existing package, install it first:
remotes::install_github("pachadotdev/cpp4r")
# or
pak::pkg_install("pachadotdev/cpp4r")
Then put your C++ files in the src/ directory and add the following to your DESCRIPTION file:
LinkingTo: cpp4r
Then decorate C++ functions you want to expose to R with [[cpp4r::register]].
cpp4r is a header only library with no hard dependencies and does not use a shared library, so it is straightforward and reliable to use in packages without fear of compile-time and run-time mismatches.
Alternatively, you can vendor the current installed version of cpp4r headers into your package with cpp4r::vendor(). This ensures the headers will remain unchanged until you explicitly update them.
Getting started
See the documentation to get started using cpp4r in your scripts, particularly if you are new to C++ programming.
Getting help
Please open an issue or email me. I will do my best to respond before 48 hours.
Contributing
Contributions are welcome! Please see the internals vignette for details about design choices and coding style.
Code of Conduct
Please note that the cpp4r project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.
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