Re: Boost.Beast state of play

From: Christopher Kohlhoff (chris_at_[hidden])
Date: 2020-07-03 01:03:58

On Fri, Jul 3, 2020, at 1:21 AM, Richard Hodges via Boost wrote:
> [...]

This post refers to unrelated things, so for clarity:

1) BOOST_ASIO_NO_DEPRECATED

The handler invocation and allocation hooks were superseded and
deprecated back in Boost 1.66, with the introduction of the networking
TS compatibility:

<https://www.boost.org/doc/libs/1_66_0/doc/html/boost_asio/net_ts.html>

The only deprecation-related change for Asio in Boost 1.74 is that
these hooks are now covered by BOOST_ASIO_NO_DEPRECATED. This will
help users find and replace their usage of the hooks in their
applications.

Beast changed to respect the definition of BOOST_ASIO_NO_DEPRECATED in
relation to these hooks.

2) BOOST_ASIO_NO_TS_EXECUTORS

With Boost 1.74, Asio adds an implementation of the proposed C++23
standard executors. This is in addition to the existing executors
implementation which is defined in the networking TS.

Most applications will require no modification, or very little. If
absolutely necessary, users can define
BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT to enable full backward
compatibility.

A user may choose to define BOOST_ASIO_NO_TS_EXECUTORS so that they
can disable networking TS executors entirely, and use only the
proposed C++23 executors. Even when this is defined, unless
interacting directly with executors at a low level, most code will
require little or no change.

Beast changed as follows:

* To support the proposed C++23 standard executors implementation as
  an additive feature.

* To respect the user's definition of BOOST_ASIO_NO_TS_EXECUTORS.

The common theme here is that these changes impact Beast more than
they will impact end users, because Beast opts to support and pass
through Asio's latest features without attenuation. This allows Beast
users to employ these latest features in their applications.

The majority of users, and especially those that define neither of the
above preprocessor macros, should experience little or no change.