RcppSpdlog 0.0.29 on CRAN: Small Enhancement

Sat, 09 May 2026 17:49:00 CDT

Version 0.0.29 of RcppSpdlog arrived on CRAN today, has been uploaded to Debian and built for r2u. The (nice) documentation site has been refreshed too. RcppSpdlog bundles spdlog, a wonderful header-only C++ logging library with all the bells and whistles you would want that was written by Gabi Melman, and also includes fmt by Victor Zverovich. You can learn more at the nice package documention site.

This release features a rewritten internal routine unpacking the R variadic arguments into C++ variadic template arguments. This in turn allows to turn back to std::format in C++ mode when C++20 is used. We also adjust for the not-quite-ready-for-this state of the x86-64 based macOS machine at CRAN. It is running a compiler and SDK choice that cannot fully deal with C++20, so we dial compilation on it down to C++17. Similarly, and as we found out after the release, Ubuntu jammy is also too old to default to std::format so we need to add a better detection here too so that we can also fall back to the included fmt there.

The NEWS entry for this release follows.

Changes in RcppSpdlog version 0.0.29 (2026-05-08)

Some small continuous integration updates

The internal formatter was rewritten as a recursive generator of variadic templates.

Switch back to std::format with C++20, but force inferior macos-release-x86_64 to use C++17 rather than default C++20 which fails

Courtesy of my CRANberries, there is also a diffstat report detailing changes. More detailed information is on the RcppSpdlog page, or the package documention site.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.