Re: [boost] [review] [sqlite]

(CC-ing the list) On Sat, 16 Nov 2024 at 12:11, Klemens Morgenstern wrote:

On Sat, Nov 16, 2024 at 7:07 PM Ruben Perez wrote:

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3. What's the rationale behind BOOST_SQLITE_NO_VIRTUAL? Wouldn't setting it cause trouble, being a compiled library?

It would. The idea is that you can use that for constrained (i.e. embedded environments) to avoid the unnecessary vtable and to enforce devirtualization if your compiler misses this.

If I have read the code correctly, these functions seem to only be used in headers. Why do they need to be virtual? It looks like it could have been made a compile-time interface (i.e. a concept), completely avoiding the need for the macro. What's the rationale behind this?

That's correct, that's also what it was originally. But the error messages were horrendous. By creating a base class you get good error messages (purely virtual because method X is missing) and the compiler is still compelled to devirtualize by the way it's used. And because it's effectively unused, you can disable it.

Couldn't you achieve a similar effect (scoped to C++20 and later) by conditionally using concepts? In a way similar to what Asio does to diagnose completion tokens (i.e. BOOST_ASIO_COMPLETION_TOKEN_FOR).