ADL

[Jacob Carlborg via Digitalmars-d]

On 2016-09-05 10:17, Andrei Alexandrescu wrote:

> Let me make sure I understand it. The core structure is this:
>
> =====
> module bob;
> struct S {}
> void f(S s);
>
> module myalgorithm;
> void test(T)(T t)
> {
>   f(t);
> }
> =====
>
> The core issue here is that f is not considered for lookup. It is a free
> function in the same module as S. That's not a frequent case and it
> seems right to not support it in the lookup rules.
>
> The simplest solution, which has already been discussed, is to make f a
> member of S. It is important that does not affect modularity; all
> protection in D has module-level granularity, so the premise of
> http://www.drdobbs.com/cpp/how-non-member-functions-improve-encapsu/184401197.
> So it's for the most part a clerical matter: move the body of f inside
> S, or if f is already generic define an alias for it inside of S.
>
> This is the baseline solution, and it is reasonable. This needs to be
> properly understood before we look into any others: by a simple
> mechanical intervention, everything works properly. Every language has
> such minute needs for minor scaffolding.
>
> It must also be understood that changing the lookup rules to make this
> scaffolding unnecessary bring with them a host of unpleasant consequences.
>
> Are we in agreement about the baseline solution?

I thought one of the reasons for UFCS was to be able to make a type 
support the range interface without modifying the type.

-- 
/Jacob Carlborg