Re: [Capy review] Some questions

On Wed, Jun 24, 2026 at 10:21 AM Peter Dimov <[email protected]> wrote:

> You need the definitions of const_buffer and mutable_buffer to be available
>  in order to see whether they have constructors from this or that, which requires
> physical coupling.
>

If const_buffer was constructible from span<byte> then this is a perfectly
valid buffer sequence which does not require physical coupling:

    array<const_buffer, 3>


> > This way we don't need the full strength of an explicit concept, yet we can
> still get the benefits.
>
> I have no idea what "full strength" there is. A concept is a concept, it's
>  not any more complicated or strong than a concrete type.
>

A concept is stronger than a concrete type because a concrete type comes in
exactly one formulation while types which satisfy a concept comes in
infinite formulations.


> You already have the concept, you just don't name it. "Convertible to const_buffer"
> is as much a concept as any other, and there's no "full" or "partial"
> strength involved anywhere.
>

"Convertible to X" feels qualitatively different to me than a concept, as
one is scoped and the other is unbounded.

Yet I accept your framing, and "convertible to X" is what Asio does, and
what we will do, so we are agreeing.

Thanks
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