[OT] Modules dropped out of C++17

[via Digitalmars-d]

On Tuesday, 9 June 2015 at 08:33:04 UTC, Kagamin wrote:
> Extension methods are conceptually the type's methods. The 
> type's interface is a conceptual thing, I don't think it has 
> anything to do with physical layout of source code.

This is a tricky issue. If you have structural typing (which 
Ada-style generics, C++ and D templates are a close, but weak, 
cousin to) then adding an extension method as a first class 
method will then change the type-resolution... which affects what 
kind of features you can have that use type resolution. Is the 
extension global or local? What if two extensions differ in 
semantics, but not in name? Not a problem for nominal typing, but 
a problem for structural/duck-like typing when you scale up.