Bjorn Reese wrote:

On 2021-02-23 19:56, Peter Dimov via Boost wrote:

...

Describe is a library that allows programmers to annotate their classes (and enumerations) in order to enable simple reflection. It provides a very important fundament on which other libraries can build upon to provide automatic support for user-defined types.

How does it differ from Boost.Fusion?

* It supports more complete metadata, such as base classes, member functions and access control. (The RPC example demonstrates a use for functions.) https://pdimov.github.io/describe/doc/html/describe.html#example_json_rpc * The metadata has the member name which enables easier access to it. In Fusion, you can retrieve the member name but it's less convenient. https://gist.github.com/meetingcpp/a06e0ca694b57afb6271445a8d833722 * Boost.Fusion gives you a Fusion sequence, which you then manipulate using Fusion primitives. Describe gives you a specific type of a documented form that can be manipulated with Mp11 primitives (as it's a type list) but can also be manipulated using ordinary C++ metaprogramming. Most simple uses require no metaprogramming at all, just an mp_for_each. The goal here is to make is as easy and painless as possible for other libraries to describe their types (in order to enable users to take advantage of the metadata). Describe is a lightweight dependency, almost standalone (only needs Mp11 at present), and will eventually become truly standalone. The aspiration here is to establish a de-facto standard for annotating types. My initial goal was also to aim for a de-jure standard eventually, i.e. add the describe_* primitives to , but given the current state of C++ reflection, realistically, this is not going to happen. But it won't hurt to still do the work as if it did have a chance to happen, because who knows.