A scoped C++ namespace symbol


D supports the following syntax to declare symbol(s) as being part of a C++ namespace:

  1. extern (C++, "myNamespace") { /+ Symbols +/ } // String variant extern (C++, SomeNamespace) { /+ Other symbols +/ } // Identifier variant
The first form is an attribute and only affects mangling, and is implemented in dmd.attrib. The second form introduces a named scope and allows symbols to be refered to with or without the namespace name, much like a named template mixin, and is implemented in this module.
  1. extern (C++, Basket) { struct StrawBerry; void swapFood (Strawberry* f1, Strawberry* f2); } void main () { Basket.StrawBerry fruit1; StrawBerry fruit2; Basket.swapFood(fruit1, fruit2); swapFood(fruit1, fruit2); }
Hence the Nspace symbol implements the usual ScopeDsymbol semantics.

Note that it implies extern(C++) so it cannot be used as a generic named scope. Additionally, Nspace with the same Identifier can be defined in different module (as C++ allows a namespace to be spread accross translation units), but symbols in it should be considered part of the same scope. Lastly, not all possible C++ namespace names are valid D identifier.


Walter Bright

Source: nspace.d

  • Declaration

    class Nspace: dmd.dsymbol.ScopeDsymbol;


    • Declaration

      Expression identExp;

      Namespace identifier resolved during semantic.