Boost.Flyweight Documentation - Release notes

# Boost.Flyweight Release notes

Future work
Index
Acknowledgements

## Contents

- Boost 1.90 release
- Boost 1.87 release
- Boost 1.83 release
- Boost 1.82 release
- Boost 1.81 release
- Boost 1.74 release
- Boost 1.73 release
- Boost 1.71 release
- Boost 1.69 release
- Boost 1.60 release
- Boost 1.58 release
- Boost 1.57 release
- Boost 1.56 release
- Boost 1.55 release
- Boost 1.45 release
- Boost 1.44 release
- Boost 1.40 release
- Boost 1.39 release
- Boost 1.38 release

## Boost 1.90 release

- Fixed compile errors in Clang 19 and later due to P0522R0 support.

## Boost 1.87 release

- Added `concurrent_factory`, a factory based on a concurrent container from Boost.Unordered that provides excellent performance in multithreaded scenarios.
- Marked as `noexcept` those `boost::flyweight` operations previously documented as not throwing (issue #15).

## Boost 1.83 release

- Added smart-pointer syntax to `boost::flyweight` (`operator*` and `operator->` dereferencing to the underlying value).
- Fixed a situation where the mutex used by `simple_locking` was not recursive (issue #12).

## Boost 1.82 release

- Maintenance work.

## Boost 1.81 release

- Maintenance work.

## Boost 1.74 release

- Maintenance work.

## Boost 1.73 release

- Maintenance work.

## Boost 1.71 release

- Maintenance work.

## Boost 1.69 release

- Fixed some issues in GCC related to Boost.MPL placeholder expression handling.
- Maintenance fixes.

## Boost 1.60 release

- Maintenance fixes.

## Boost 1.58 release

- Added hash support both with `std::hash` and `boost::hash`. This can be optionally disabled to avoid clashes with legacy code where this support has already been defined by the user.
- Maintenance fixes.

## Boost 1.57 release

- Added serialization support via Boost Serialization.
- `flyweight` default constructor was made `explicit` in Boost 1.56, which introduces a regression in some initialization scenarios. The former non-`explicit` default constructor has been restored (ticket #10439).

## Boost 1.56 release

- In compilers with variadic template support, `boost::flyweight<T>` now provides a perfectly forwarding constructor to `T::T` (previously an emulation was used).
- `flyweight` now replicates the initializer-list constructors and assignment operators of its underlying type.
- Fixed intermodule static initialization problem (ticket #9553).
- Maintenance fixes.

## Boost 1.55 release

- Maintenance fixes.

## Boost 1.45 release

- Fixed a hanging problem with `intermodule_holder` in Win32 platforms related to a Boost.Interprocess issue described at ticket #4606.
- Removed an internal assertion incompatible with program termination via `std::exit`.

## Boost 1.44 release

- Fixed an incorrect mode of usage of Boost.Variant in one of the examples.

## Boost 1.40 release

- Maintenance fixes.

## Boost 1.39 release

- The `refcounted` component was not thread-safe due to an incorrect implementation and could deadlock under heavy usage conditions. This problem has been corrected.

## Boost 1.38 release

- Initial release of Boost.Flyweight.

Future work
Index
Acknowledgements

Revised September 20th 2025

© Copyright 2006-2025 Joaquín M López Muñoz. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)