refactor: rename connection creation methods (#406)

This PR makes things around connection factories a little more consistent and more intuitive:

    * createConnection() has been removed. One shall call more expressive createSystemConnection() instead to get a connection to the system bus.
    * createDefaultBusConnection() has been renamed to createBusConnection(), so as not to be confused with libsystemd's default_bus, which is a different thing (a reusable thread-local bus).

Proxies still by default call createBusConnection() to get a connection when the connection is not provided explicitly by the caller, but now createBusConnection() does a different thing, so now the proxies connect to either session bus or system bus depending on the context (as opposed to always to system bus like before).

src/Connection.cpp

@@ -872,14 +872,6 @@ int IConnection::PollData::getPollTimeout() const
 
 namespace sdbus::internal {
 
-std::unique_ptr<sdbus::internal::IConnection> createConnection()
-{
-    auto connection = sdbus::createConnection();
-    SCOPE_EXIT{ connection.release(); };
-    auto connectionInternal = dynamic_cast<sdbus::internal::IConnection*>(connection.get());
-    return std::unique_ptr<sdbus::internal::IConnection>(connectionInternal);
-}
-
 std::unique_ptr<sdbus::internal::IConnection> createPseudoConnection()
 {
     auto interface = std::make_unique<sdbus::internal::SdBus>();
@@ -892,25 +884,15 @@ namespace sdbus {
 
 using internal::Connection;
 
-std::unique_ptr<sdbus::IConnection> createConnection()
-{
-    return createSystemBusConnection();
-}
-
-std::unique_ptr<sdbus::IConnection> createConnection(const std::string& name)
-{
-    return createSystemBusConnection(name);
-}
-
-std::unique_ptr<sdbus::IConnection> createDefaultBusConnection()
+std::unique_ptr<sdbus::IConnection> createBusConnection()
 {
     auto interface = std::make_unique<sdbus::internal::SdBus>();
     return std::make_unique<sdbus::internal::Connection>(std::move(interface), Connection::default_bus);
 }
 
-std::unique_ptr<sdbus::IConnection> createDefaultBusConnection(const std::string& name)
+std::unique_ptr<sdbus::IConnection> createBusConnection(const std::string& name)
 {
-    auto conn = createDefaultBusConnection();
+    auto conn = createBusConnection();
     conn->requestName(name);
     return conn;
 }

src/IConnection.h

@@ -98,7 +98,6 @@ namespace sdbus::internal {
                                                         , void* userData ) = 0;
     };
 
-    [[nodiscard]] std::unique_ptr<sdbus::internal::IConnection> createConnection();
     [[nodiscard]] std::unique_ptr<sdbus::internal::IConnection> createPseudoConnection();
 
 }

src/Proxy.cpp

@@ -310,7 +310,7 @@ std::unique_ptr<sdbus::IProxy> createProxy( std::unique_ptr<IConnection>&& conne
 std::unique_ptr<sdbus::IProxy> createProxy( std::string destination
                                           , std::string objectPath )
 {
-    auto connection = sdbus::createConnection();
+    auto connection = sdbus::createBusConnection();
 
     auto sdbusConnection = std::unique_ptr<sdbus::internal::IConnection>(dynamic_cast<sdbus::internal::IConnection*>(connection.release()));
     assert(sdbusConnection != nullptr);
@@ -324,7 +324,7 @@ std::unique_ptr<sdbus::IProxy> createProxy( std::string destination
                                           , std::string objectPath
                                           , dont_run_event_loop_thread_t )
 {
-    auto connection = sdbus::createConnection();
+    auto connection = sdbus::createBusConnection();
 
     auto sdbusConnection = std::unique_ptr<sdbus::internal::IConnection>(dynamic_cast<sdbus::internal::IConnection*>(connection.release()));
     assert(sdbusConnection != nullptr);