// sample-module.cppm: a C++20 module interface unit.
// Free sample from 99helpers.com/file-types/cpp
//
// sample-module-main.cpp imports it. Modules need the module compiled
// before the files that import it; build systems such as CMake (3.28 and
// later) work out that order for you. By hand:
//   GCC:    g++ -std=c++20 -fmodules-ts -x c++ sample-module.cppm -x none sample-module-main.cpp -o greet
//   Clang:  clang++ -std=c++20 --precompile sample-module.cppm -o greetings.pcm
//           clang++ -std=c++20 -fmodule-file=greetings=greetings.pcm sample-module-main.cpp greetings.pcm -o greet
//   MSVC:   rename it to sample-module.ixx, Visual Studio's extension for
//           module interfaces, and build both files in one project.

// The global module fragment: where classic #include lines belong.
module;
#include <string>
#include <string_view>

// The module declaration names the module that importers ask for.
export module greetings;

// Only exported names are visible to importers.
export namespace greetings {

std::string hello(std::string_view name);

inline constexpr int version = 1;

}  // namespace greetings

// Not exported: a helper that importers can't see or call.
static std::string decorate(std::string_view text)
{
    return "*** " + std::string{text} + " ***";
}

std::string greetings::hello(std::string_view name)
{
    return decorate("Hello, " + std::string{name} + "!");
}