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[release] Master branch is now open for bug fixes
by Marshall Clow 17 Mar '25

17 Mar '25

Hi, The master branch is now open for bug fixes, test and documentation changes, but please follow the policy described in: https://github.com/boostorg/wiki/wiki/Releases%3A-Beta-Merge-Policy The next deadline: On April 2nd, master closes for all changes. As always, the calendar is at https://www.boost.org/development/ — The release managers

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boost::python and Python 3.12
by Tom Kacvinsky 17 Mar '25

17 Mar '25

While working on a project to upgrade an embedded Python interpreter (to Python 3.12), which uses boost::python, I noticed the structs from the Python C API now have more members and those extra struct members were not populated in the boost::python code. In particular I was bit by the enum module crashing our application startup. I noticed this with boost 1.78, but I found the same problematic code in the release that was current as of two months ago (1.87.0, I think). I got things to compile and run, but my approach was to just make the code Python 3.12 compliant. I can prepare a patch that has the appropriate macro guards for populating the structs as they relate to different Python versions. I'll read the boost developers guide and follow the necessary steps to submit a fix. Regards, Tom

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release] Boost 1.88.0 beta 1 released
by Marshall Clow 16 Mar '25

16 Mar '25

Boost release 1.88.0 beta 1 is now available at: https://archives.boost.io/beta/1.88.0.beta1/source/ The SHA256 checksums are: bc4948bc664fde0c2142badae2679a42124b464dc58019250afe0ef57fd7763e boost_1_88_0_rc1.zip 3c334a9a743b68a35452b0223be8932fb39f26a6938382f9b9e625c4df99602c boost_1_88_0_rc1.tar.gz 9e42c0611500151d795d66a07ef0a21036c02d24678e2e887caf6d97fcbc25ca boost_1_88_0_rc1.tar.bz2 7faf60c4cb12ee90270e41716cf3735a8739016d7346983ce9f5e899e510b26d boost_1_88_0_rc1.7z Release notes (still need updates): https://www.boost.org/users/history/version_1_88_0.html Please try the beta and report any problems you encounter. Thanks to everyone who contributed to the release. -- Boost Release Team

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[release] Boost 1.88.0 Release Candidate 1 is available
by Marshall Clow 14 Mar '25

14 Mar '25

Available at: https://archives.boost.io/beta/1.88.0.beta1/source/ The SHA256 checksums are as follows: bc4948bc664fde0c2142badae2679a42124b464dc58019250afe0ef57fd7763e boost_1_88_0_b1_rc1.zip 3c334a9a743b68a35452b0223be8932fb39f26a6938382f9b9e625c4df99602c boost_1_88_0_b1_rc1.tar.gz 9e42c0611500151d795d66a07ef0a21036c02d24678e2e887caf6d97fcbc25ca boost_1_88_0_b1_rc1.tar.bz2 7faf60c4cb12ee90270e41716cf3735a8739016d7346983ce9f5e899e510b26d boost_1_88_0_b1_rc1.7z As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release Managers

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[proposal] OpenMethod library
by Jean-Louis Leroy 11 Mar '25

11 Mar '25

Hello Boost developers! I would like to propose my open-method library for inclusion in Boost. Open-methods are an elegant solution to the Expression Problem: > Given a set of types, and a set of operations on these types, is it possible > to add new operations on the existing types, and new types to the existing > operations, without modifying existing code? Open-methods solve the Expression Problem by making it possible to define free virtual functions, i.e. virtual functions that exist outside of a class. They also help reduce coupling. Open-methods are often called "multi-methods", because they typically make it possible to select an overrider on the basis of more than one argument (as this library does). Nice, but this is a distraction. Observations show that single dispatch largely outnumbers multiple dispatch in real systems, even in languages that natively support multi-methods (Common Lisp, Clojure, Julia, Dylan, TADS, Cecil, Diesel, Nice, etc). "Multi" is just the cherry on the "open" cake. Bjarne Stroustrup wanted open-methods in C++ almost from the beginning. In D&E he writes: > I repeatedly considered a mechanism for a virtual function call based on more > than one object, often called multi-methods. [...] Since about 1985, I have > always felt some twinge of regret for not providing multi-methods. > Stroustrup, 1994, The Design and Evolution of C++, 13.8. Circa 2007, he tried to bring open-methods into the standard, unfortunately without success, to his enduring regret. Decades later he writes: > In retrospect, I don’t think that the object-oriented notation (e.g., x.f(y)) > should ever have been introduced. The traditional mathematical notation f(x,y) > is sufficient. As a side benefit, the mathematical notation would naturally > have given us multi-methods, thereby saving us from the visitor pattern > workaround. > Stroustrup, 2020, Thriving in a Crowded and Changing World: C++ 2006–2020. This is what this library is all about: f(x, y), and getting rid of visitors. It closely follows the design described in the papers by Stroustrup and his PhD students Peter Pirkelbauer and Yuriy Solodkyy. Method dispatch is *fast*. It uses v-tables similar to native virtual functions, and it can match their performance. The library also provides additional features: a mechanism to call the next most specialized overrider, support for smart pointers, customization points for alternative RTTI systems, error handling, tracing, etc. The library requires C++17 or above. It supports virtual and multiple inheritance, excluding repeated inheritance. For evaluation purposes, I prepared a repository with a library adapted to Boost naming conventions: https://github.com/jll63/Boost.OpenMethod. The documentation is here: https://jll63.github.io/Boost.OpenMethod. Here are a few examples from the tutorial on Compiler Explorer: * Hello World: https://godbolt.org/z/9hv8oE8zd * AST - combining virtual_ptr and std::unique_ptr: https://godbolt.org/z/cPjzfanc8 * Intrusive vptr: https://godbolt.org/z/87h9zv7dK * Policy for throwing exceptions: https://godbolt.org/z/nEYWGsPc5 If you like what you see, please consider endorsing the library. Thanks, Jean-Louis Leroy

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[Release] Master branch is now closed for the beta release
by Marshall Clow 09 Mar '25

09 Mar '25

Master is closed for all changes. See the release schedule at: https://www.boost.org/development/index.html -- Release managers

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[release] Master branch closes for the 1.88.0 beta release on SATURDAY (March 8)
by Ion Gaztañaga 06 Mar '25

06 Mar '25

Hi, Due to some unexpected delays, the master branch will close on SATURDAY (March 8). — The Release Managers

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MAP and Vector clear is not releasing memory
by Murali Kishore 26 Feb '25

26 Feb '25

Hi, map and vector stored in shared memory using boost apis and called clear to release memory. when i insert same key i see old data present. want to check using boost map.clear or vec.clear is not removing content. Example: pod_list[] (vector contains following 3 members) pod_info { pod_id du_map. cell_map. } Step 1: Added elements Step 2: pod_list.clear(); Step 3: observed no elements in pod_list empty Step 4: Added only key pod_info.pod_id = 1; pod_list.insert(pod_info); Step 5: i see old content map to this pod_id. after this expecting du_map.size and cell_map size is empty. but du_map,cell_map content is same as before clear want to check is clear will not remove memory? is any other best way to clean this vector. -- Regards, Murali Kishore

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Master branch now closed for new libraries and breaking changes
by Marshall Clow 26 Feb '25

26 Feb '25

Welcome to the start of the 1.88.0 release cycle. The release branch is now closed for new libraries and breaking changes to existing libraries. Still open for bug fixes and other routine changes to all libraries without release manager review. The next deadline is next Wednesday, when the release branch will be closed for major changes. As always, the calendar is here: https://www.boost.org/development/index.html — The release managers

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Master branch closing for major changes TOMORROW
by Marshall Clow 26 Feb '25

26 Feb '25

After tomorrow: Release branch closed for major code changes. Still open for serious problem fixes and docs changes without release manager review. Next milestone:March 5th - Release closed for all changes (for 1.88.0 beta 1) Calendar is here: https://www.boost.org/development/ — The release managers

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