Namespaces in C++ are used to ensure the symbols in a library will not conflict with any symbols in another library. Fortran and Python both use a module to accomplish the same thing.

The global variable namespace is a blank delimited list of namespaces used as the initial namespace. This namespace will be used when accessing symbols in the library, but it will not be used when generating names for wrapper functions.

For example, the library wrapped is associated with the namespace outer. There are three functions all with the same name, worker. In C++ these functions are accessed by using a fully qualified name: outer::worker, outer::innter1::worker and outer::inner2::worker.

namespace outer {
  namespace inner1 {
    void worker();
  } // namespace inner1

  namespace inner2 {
    void worker();
  }  // namespace inner2

  void worker();
} // namespace outer

The YAML file would look like:

library: wrapped
namespace: outer
  C_prefix: WWW_

- decl: namespace inner1
  - decl: void worker();
- decl: namespace inner2
  - decl: void worker();
- decl: void worker();

For each namespace, Shroud will generate a C++ header file, a C++ implementation file, a Fortran file and a Python file. The nested namespaces are added to the format field C_name_scope.

For the C wrapper, all symbols are globally visible and must be unique. The format fields C_prefix and C_name_scope are used to generate the names. This will essentially “flatten” the namespaces into legal C identifiers.

void WWW_worker();
void WWW_inner1_worker();
void WWW_inner2_worker();

In Fortran each namespace creates a module. Each module will have a function named worker. This makes the user responsible for distinguising which implementation of worker is to be called.

subroutine work1
  ! Use a single module, unambiguous
  use wrapped_mod
  call worker
end subroutine work1

subroutine work2
  ! Rename symbol from namespace inner1
  use wrapped_mod
  use wrapped_inner1_mod, inner_worker => worker
  call worker
  call inner_worker
end subroutine work2

Each namespace creates a Python module.

import wrapped

Several fields in the format dictionary are updated for each namespace: namespace_scope, C_name_scope, F_name_scope.

std namespace

Shroud has builtin support for std::string and std::vector.