On Fri, Mar 26, 2021 at 3:50 PM Ville Voutilainen via SG7 <
sg7_at_[hidden]> wrote:

> On Fri, 26 Mar 2021 at 21:32, Barry Revzin via SG7 <sg7_at_[hidden]>
> wrote:
> >
> >
> >
> > On Fri, Mar 26, 2021 at 2:00 PM David Rector via SG7 <
> sg7_at_[hidden]> wrote:
> >>
> >> Attached is a new paper addressing how the P2237/P2230 facilities might
> be expanded to be able handle the `Sum<T,U>` example discussed awhile back,
> and more generally subsume the capabilities of the "string-injection"
> approach, while avoiding its drawbacks.
> >
> >
> > Hi David,
> >
> > I didn't understand the Sum<T, U> example before and I still don't.
> There's not really a description of it in the paper, just a lot of code.
> What problem is it demonstrating?
>
> I don't understand the lack of understanding. It's basically
>
> For two types T and U
> - generate a product-type wrapper X that
> * for every member function $foo appearing in both T and U, has a
> member function X::$foo that returns the sum of the results of T::$foo
> and U::$foo
> * otherwise, for any member function $bar appearing in just one of
> T and U, has a member function X::$bar that returns the result of
> either T::$bar
> or U::$bar depending on which one is present
>
> It's just an example of a wrapper like that, a particular kind of
> mediator, where the API is the union of the APIs of the mediated
> types.
>


This is an explanation I can understand!

-- 
Be seeing you,
Tony