Engine::Engine(int* argc, char** argv) : pimpl(new kernel::EngineImpl())
{
xbt_assert(Engine::instance_ == nullptr, "It is currently forbidden to create more than one instance of s4u::Engine");
Engine::Engine(int* argc, char** argv) : pimpl(new kernel::EngineImpl())
{
xbt_assert(Engine::instance_ == nullptr, "It is currently forbidden to create more than one instance of s4u::Engine");