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

[Walter Bright]

On 8/1/2018 7:09 PM, Rubn wrote:
> On Wednesday, 1 August 2018 at 23:04:01 UTC, Walter Bright wrote:
>> An example of silent hijacking:
>>
>>    extern (C++, "ab") void foo(long); // original code
>>    ... lots of code ...
>>    extern (C++, "cd") void foo(int); // added later by intern, should have been
>>                                      // placed in another module
>>    ... a thousand lines later ...
>>    foo(0); // OOPS! now calling cd.foo() rather than ab.foo(), D sux
>>
>> You might say "nobody would ever write code like that." But that's like the C 
>> folks saying real C programmers won't write:
> 
> You can do that today, just remove the "extern(C++, ...)" part and you have the 
> same issue. Why should C++ with namespaces be safer than just regular D ? I 
> don't understand, if it is such a huge gigantic problem why didn't you do 
> anything to solve this problem in regards to D then ?

The difference is those names are supposedly in different namespaces, given that 
the code is converted from C++:

     namespace ab { void foo(long); }
     ... lots of code ...
     namespace cd { void foo(int); }

where the foo()'s do not conflict with each other, and a user would reasonably 
expect that same behavior when translated to D.


If you *want* them in the same scope in D, you can do that with alias.