Is there any good reason why C++ namespaces are "closed" in D?

[Mathias Lang]

On Tuesday, 31 July 2018 at 06:12:40 UTC, Walter Bright wrote:
>
> Thirdly, C and C++ are loaded to the gills with 
> seemed-like-a-good-idea-at-the-time solutions that turned out 
> to have bad unintended consequences that bork up the language 
> for everyone down the line. D has some of those, too.

And only experience can tell if those ideas turn out to be bad, 
as people make use of it and realize how (im)practical they are.

We only got a handful known serious users of `extern (C++)` on 
Windows, and probably only me on POSIX (because anything 
templated doesn't mangle properly on POSIX, so the STL is 
unusable).

So if all users come together to say that the current design 
seemed-like-a-good-idea-at-the-time (to you) but is not, and 
could be *simplified* to yield a better product, it sounds very 
backward to not listen to them.