August 2025 - Boost - lists.boost.org

A proposal for a modern build-system
by Hassan Sajjad 08 Dec '25

08 Dec '25

Hi. I compiled 25 Boost libraries with C++20 header-units, including examples and Tests of a few. This resulted in a 1.44x speed-up if we exclude the scanning. Scanning was as slow as the header-unit build. I have a solution for that. I am sending this paper (Making some final edits) https://htmlpreview.github.io/?https://github.com/HassanSajjad-302/iso-pape… , which allows for a build-system to use a scanning-less approach to build header-units.This method requires only minimal modifications to the compiler and enables memory-mapped file sharing, which significantly reduces filesystem overhead and further boosts speed. My proposal for a scanning-less approach will allow HMake to have another amazing feature, monolithic Big header-units. BigHu will allow you to map all the headers from a directory to a single header-unit. This header-unit includes all these header-files and consumes them as header-files. Now, whenever the compiler requests a header-unit from this directory, the build-system instead sends this consolidated BigHu. This will not only improve the clean build speed, because of fewer process launches. But also massively boosts the rebuild speed as few header-units need to be read instead of lots of files. No source-code editing will be needed to use this feature. And you will have the option to either build a library as BigHu (if you don't mean to edit it) or as small header-units (if you are working on it). HMake will soon support compile_commands.json, which I guess can work fine with header-units. Thus you can benefit from both, faster compilation and working intelliscence. The API shown in hmake.cpp is a work in progress. HMake build-system benefits are numerous, even if we leave out the header-units support. This makes it a perfect replacement for B2. I believe we can complete the switch in the next 2 months. And if some compiler supports my paper, we get >3x faster compilation as well. Best, Hassan Sajjad

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Senior students eager to write a graduation work
by Antony Polukhin 25 Sep '25

25 Sep '25

Hi, I've got in touch with some professors in IT universities. They have a bunch of senior students that are in search of projects for their graduation work. Seems that Boost Libraries could benefit from that. Mentoring a senior student usually takes less time than implementing something on your own. Do you have any Boost related projects that could be done by students? Is there a list of such projects and mentors anywhere? -- Best regards, Antony Polukhin

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[sqlite] Formal review of Boost.SQLite begins
by Mohammad Nejati [ashtum] 12 Sep '25

12 Sep '25

Dear Boost community, The review of Boost.SQLite by Klemens Morgenstern begins today, Monday, August 25, and runs through Wednesday, September 3, 2025. Boost.SQLite provides a safer and more expressive C++ interface to the SQLite3 C-API to simplify usage and reduce errors. You can read the documentation at: https://klemens.dev/sqlite and study or try out the code at: https://github.com/klemens-morgenstern/sqlite This is the second review attempt. The first concluded without a result due to too few submitted reviews. Anyone with experience in C++ or SQLite, at any level, is encouraged to contribute. In your review, please indicate how much time you spent on the evaluation. Here are some questions you might find helpful when writing your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? Do you already use it in industry? - Did you try to use the library? With which compiler(s)? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? At the end of your review, please state clearly whether you ACCEPT, REJECT, or CONDITIONALLY ACCEPT (with explicit conditions) the proposed Boost.SQLite library. Your feedback is critical to the success of this review. Thank you in advance for your time, expertise, and contributions. Best regards, Mohammad Nejati Review Manager for the proposed Boost.SQLite

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Just testing out mailman.. ignore. :-)
by René Ferdinand Rivera Morell 02 Sep '25

02 Sep '25

Some HTML things.. - A bullet list. - Second item. A number list.. 1. Uno 2. Dos Some *different* *formatting* for *words* and such. -- -- René Ferdinand Rivera Morell -- Don't Assume Anything -- No Supongas Nada -- Robot Dreams - http://robot-dreams.net

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[boost][sqlite] some feedback on the docs
by Andrzej Krzemienski 30 Aug '25

30 Aug '25

Hi Everyone, First, I wanted to thank Klements for writing and sharing Boost.SQLite and for submitting it for the review. This is by no means a review. But I have started reading the docs and I have some initial feedback that I wanted to share. I am not familiar with sqlite3 interface, so I am reading the docs from the perspective of someone new. [1] Reference section in the documentation is insufficient. With a C++ mindset, I tried to figure out how the session management works, and the documentation of sqlite/connection.hpp does not help me. I cannot find if the resources are allocated in the constructor. Any constructor? Why do you have two? Why do you have a separate function connect()? What is the purpose of having a constructor if I still need to call connect()? According to the docs, connection class has no destructor,from which I gather that I have to manage the session lifetime manually and close it with function close(). If any other function throws an exception, I will not be able to close the connection. Is that intended? There are actually two functions: release() and close(). The docs do not tell me how they differ and which one I should use and when: how is releasing the handle in class connection different from closing the connection? I also cannot see what exception type is thrown from connection functions and under what conditions. The constructor taking handle_type: where would I use it? Or maybe it is only intended to be called by macros? function valid(): not clear what is an d is not valid in this context: does this indicate the default-constructed state, or is it a term specific to sqlite? [2] Dragging the entire <sqlite3.h> The names like SQLITE_OPEN_READWRITE seem to come from <sqlite3>. So this library indirectly drags the entire <sqlite3.h>, and all the declarations into the global namespace. Is this necessary? One could imagine an alternative when this is only included in the library cpp files. No? In any case, this should be documented. [3] It is interesting that "virtual table" has one meaning in the sqlite world and another in the C++ world: a virtual pointer table. Maybe the docs should highlight that. [4] Exposing sqlite for non-eponymous tables https://klemens.dev/sqlite/#non_eponymous_tables I am reviewing this in a hurry, so maybe I am missing something obvious, but it looks to be like this lib could offer an interface that does not use sqlite types, but their Boost.Sqlite wrappers instead: It could be just a pair of two functions -- you do not have to derive from anything. The example has: struct csv_module final : sqlite::vtab::module<csv_table>{ // create the csv file sqlite::result<table_type> What are csv_table and table_type? Regards, &rzej;

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Problem: Mailing List Moderation
by Vinnie Falco 29 Aug '25

29 Aug '25

As far as I know there are two designated moderators for the list: Glen Fernandes, and John Maddock. Possibly there is a third, Marshall Clow, although this isn't clear from the website. Regardless, we have a problem where new people are coming to the list and getting moderated. I have brought in several first-time mailing list posters (and first-time review participants, via Boost.SQLite). They have all reported problems where their messages are stuck in the moderation queue. If we are to bring vital new participation on the mailing list, we need to improve their experience. I'm not sure what the best solution is. Thanks

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Re: [sqlite] Formal review of Boost.SQLite begins
by amlalelmahrouss＠icloud.com 27 Aug '25

27 Aug '25

> May I ask why? I am not hiding the implementation (i.e. sqlite3) on > purpose, so that users can just use the sqlite3 API or another library if > they need. Hiding types such as `sqlite3` with a `void*` in that case would be beneficial, as you would make the user's life easier because they would treat the `handle_type` as a handle, not a specific type accessible by the user. So as the implementer you would be able to extend the library without breaking changes. > Not being able to do that has caused me much frustration in other libraries > before. May I ask about what specific libraries you have in mind? > Which usage do you have in mind? As a query builder? Indeed, The query_builder object takes a `connection` object in the constructor. And that can be swapped with another `connection` when needed. ```cpp class query_builder { public: /// operator<< query_builder& operator<<(const cstring_ref& sql_query); /// operator>> query_builder& operator>>(resultset& res_out); }; /// example void cache_manager::read_local_cache() { resultset res{}; cstring_ref in = "SELECT * FROM cache WHERE key = \"?\""; this->builder_ << in; this->builder_ >> res; } ``` > Thank you for your review! It is my pleasure! Amlal

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Re: [sqlite] Formal review of Boost.SQLite begins
by amlalelmahrouss＠icloud.com 27 Aug '25

27 Aug '25

# Introduction Below is my review of the boost_sqlite library. First off, I believe that this approach of providing a safer and much more expressive C++ interface on top of the SQLite C library, is a step toward the simplification and hardening of database development. ## Author's Background I'm a professional C++ Developer. I've been using the Boost library in both hobby projects and professional ones. I have experience in interacting with similar connectors such as: ADO, ODBC, MySQL, JDBC. ## Initial Thoughts and Use Case The library wraps the standard C API of SQLite into wrapped containers. Such as the connection, field, resultset containers. String helpers and the connection object seems to fulfill their duty correctly. Reflecting industry standard practice of such interfaces. The library is a perfect solution for applications written in C++ with persistence needs without the need of a SQL server. Moreover the boost style codebase makes it even easier to integrate into such applications. ## Thoughts on Design The design is simple, easy to understand, and what I'd expect for such an interface. I believe it would meet my needs. ## Improvements Needed The `handle_type` alias shall be set to a void* in order to hide the implementation details of the library. ```cpp using handle_type = void*; ``` The `connection` constructor with the `int flags` parameter should be abstracted away in a `enum class` as in the following: ```cpp enum class open_flags : int { bad = 0, rw = SQLITE_OPEN_READWRITE, ... } ``` ## Notes on Documentation The readme explains the concepts and gives concrete usage examples of the interface. ```cpp conn.execute(R"( create table if not exists author ( id integer primary key autoincrement, first_name text, last_name text ); create table if not exists library( id integer primary key autoincrement, name text unique, author integer references author(id) ); )" ); ``` ## Comparison to other libraries I notice that other libraries are using the `operator<<` that would be beneficial to Boost.SQLite as well, as it would mean seamless integration into many codebases. As well as future extension capabilities, if there is a need to extend the library in the future. ## Personal Usage Although I did not use Boost.SQLite directly in any production projects, I did study its design, and run its examples with the previous experience I have with other similar libraries in mind. ## Final Thoughts The need of a modern interface for such databases is becoming stronger by the day, the C API of SQLite makes the functionality of persistence and error handling very hard in modern C++ codebases. I would like to see the library with optional dependencies as well I am favorable in the merging of this library in Boost, however improvements in additional operators might be needed for completeness. (such as operator<<, operator>>) Amlal El Mahrouss.

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Forking Asio
by Vinnie Falco 26 Aug '25

26 Aug '25

I would like to measure the interest in a fork of Asio, proposed as a Boost library for review. Currently, Boost.Asio (and the standalone version Asio) is developed and maintained by Christopher Kohlhoff. Unfortunately he has a well-earned reputation for being unresponsive to emails and GitHub issues. For example: https://github.com/chriskohlhoff/asio/pull/904 I believe that Asio is Boost's most valuable asset, because "the C++ Standard cannot connect to the Internet." Every other language has portable networking built-in except for C++. Asio is the industry standard and the gold standard for portable networking, yet it is falling behind due to its lack of evolution. A major component of my revitalization plan for Boost is to promote Asio and build many great things on top of it. For example, clients and servers which speak MCP ("Model Context Protocol"), empowering users to easily connect and talk to AI endpoints (Large Language Models) using REST and JSON. Learn more about MCP here: https://www.pulsemcp.com/ In discussions with our staff engineers, there is a movement to propose a Boost.Crypt library with cryptographic primitives as an alternative to OpenSSL, with the goal of modern interfaces which eliminate broad categories of undefined behavior and usage errors which lead to vulnerabilities. Yet if Asio cannot adopt support for alternatives to OpenSSL we cannot evolve. The fork of Asio is just in the idea stage, no work has been done yet, and it is all open to debate and design. My thinking of how the fork would work goes like this: 1. C++ Alliance allocates dedicated staff to maintain the fork 2. Stakeholders come together, on the mailing list and through GItHub issues, to determine what directions we might like to explore or move towards 3. Dedicated staff implement the work and provide support for stakeholders 4. Changes in Asio would be adopted on an as-needed basis The first order of business would be to go through all of the GitHub issues in Asio and address them one by one. What do you think?

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(no subject)
by amlalelmahrouss＠icloud.com 26 Aug '25

26 Aug '25

Hi my name is Amlal El Mahrouss and I'm interested in joining this community.

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[release] Boost 1.89.0 Release Candidate 1 is available
by Marshall Clow 25 Aug '25

25 Aug '25

The first release candidates for the 1.89.0 release are now available at: <https://archives.boost.io/release/1.89.0/source/> The SHA256 checksums are as follows: d8b0c1d593d68fe359616aa2fae4b3e258ca1f90ed57eb46c5494c29cdd1d49d boost_1_89_0_rc1.7z 9de758db755e8330a01d995b0a24d09798048400ac25c03fc5ea9be364b13c93 boost_1_89_0_rc1.tar.gz 85a33fa22621b4f314f8e85e1a5e2a9363d22e4f4992925d4bb3bc631b5a0c7a boost_1_89_0_rc1.tar.bz2 77bee48e32cabab96a3fd2589ec3ab9a17798d330220fdd8bde6ff5611b4ccde boost_1_89_0_rc1.zip 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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Boost 1.90.0 Release Notes
by Sam Darwin 21 Aug '25

21 Aug '25

Boost 1.90.0 should be able to use the new process for Release Notes. This is already enabled in the code. - Create a release notes file boost_1_90_0.adoc at https://github.com/boostorg/website-v2-docs/tree/develop/release-notes/boos… . PRs go to the 'develop' branch. - Admins merge to the master branch of website-v2-docs once a week. - Github Actions automatically uploads that to s3. /release-notes/master/boost_1_90_0.adoc - website-v2 versions/releases.py will discover the adoc. If that file exists it takes precedence over the previous methods. Let's be sure a file is there during the beta release.

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[Release] The master branch is now open
by Marshall Clow 15 Aug '25

15 Aug '25

Thank to everyone for their patience. The next release cycle will begin in late October — The release managers

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[release] Boost 1.89.0
by Marshall Clow 15 Aug '25

15 Aug '25

Release 1.89.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. The release contains one new library: * Bloom: Bloom filters, from Joaquín M López Muñoz. as well as numerous enhancements and bug fixes for existing libraries. For details, including download links, see <http://www.boost.org/users/news/version_1.89.0> You can also download directly from: <https://archives.boost.io/release/1.89.0/source/> To install this release on your system, see <http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. -- The Boost Release Team Marshall Clow, Glen Fernandes, Ion Ion Gaztañaga

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Updated Release Links
by Robert Beeston 14 Aug '25

14 Aug '25

Good day, There were some issues with the release links, the corrected ones are below: For details, including download links, see https://www.boost.org/releases/1.89.0/ You can also download directly from: https://archives.boost.io/release/1.89.0/source To install this release on your system, see http://www.boost.org/doc/user-guide/getting-started.html *Rob Beeston* Creative Director C++ Alliance cppalliance.org

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Release Report for v1.89
by Robert Beeston 14 Aug '25

14 Aug '25

Here is the link for the 1.89 Release Report: https://downloads.cppalliance.org/reports/boost_1_89_0_release_report.pdf Please let us know if you have suggestions for future reports! *Rob Beeston* Creative Director C++ Alliance cppalliance.org

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Why no "w != NULL" assertion before boost/intrusive/rbtree_algorithms.hpp:511 like before the line 476?
by achinkoff＠gmail.com 12 Aug '25

12 Aug '25

Boost version: latest release file: boost/intrusive/rbtree_algorithms.hpp function: rebalance_after_erasure_restore_invariants in this if-branch ``` if(x == x_parent_left){ //x is left child ``` there is "w != NULL" assertion before variable 'w' access: ``` BOOST_INTRUSIVE_INVARIANT_ASSERT(w); if(NodeTraits::get_color(w) == NodeTraits::red()){ ``` but in else-branch there is no same assertion before variable 'w' access: ``` if(NodeTraits::get_color(w) == NodeTraits::red()){ ``` Why? Are there no assertion in else-branch intentionally due to the rbtree structure itself? Thanks.

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[release] Master branch is now closed for the release
by Marshall Clow 07 Aug '25

07 Aug '25

Master is closed for all changes. See the release schedule at http://www.boost.org/calendar — The release managers

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C++26 Reflection in Boost
by Vinnie Falco 06 Aug '25

06 Aug '25

Which Boost libraries would benefit from implementing C++26 reflection? For my libraries that includes: Boost.JSON what other libraries?

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[release] The Master branch will be closing for the 1.89.0 release on Wednesday, 6-August
by Marshall Clow 06 Aug '25

06 Aug '25

Calendar is here: https://www.boost.org/calendar Current status of the master branch: Master is open for bug fixes and documentation updates. Other changes by permission of a release manager. — The release managers

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New and Improved Decimal Library
by Matt Borland 02 Aug '25

02 Aug '25

It has been about 6 months since the indeterminate end of the Decimal review, but Chris and I wanted to announce the newest major version of the library (v5.0.0). What has changed? Quite a lot: Breaking Changes: - Based on bitwise comparisons with other similar libraries and database software, we have changed the internal encoding of our IEEE 754-compliant types - We spent about 3 months optimizing just back end integer types that are now used throughout the library and as the internals of decimal128_t - We have changed the type names to better match conventions: - decimalXX is now decimalXX_t - decimalXX_fast is now decimal_fastXX_t - The headers have been similarly renamed, and can now be used independently instead of requiring the monolith based on feedback in Review - Constructors have been simplified to reduce confusion Other Changes: - The doc content have been overhauled thanks to feedback from Peter Turcan and others during the review - The docs are no longer a single long page of Asciidoc; we have moved to Antora. Thanks to Joaquín and Christian for making it trivial to copy from Unordered to make that happen. - https://develop.decimal.cpp.al/ - We now support formatting with {fmt} - Benchmarks have been expanded to include GCC _Decimal types, and Intel's libbid. I think people should be pleased with the results now, since that was a huge point of contention at the end of the review - Every post-review issue John was kind enough to consolidate and open have been addressed Thanks to all those that helped make the library better than it was. Let us know if you find any new issues, or need a feature, as you try the new version. Chris and I are thinking about doing the re-review in the Fall; stay tuned. Matt

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