DataFlash: add static create method

libraries/DataFlash/DataFlash.cpp

@@ -48,6 +48,18 @@ const AP_Param::GroupInfo DataFlash_Class::var_info[] = {
     AP_GROUPEND
 };
 
+DataFlash_Class::DataFlash_Class(const char *firmware_string, const AP_Int32 &log_bitmask)
+    : _firmware_string(firmware_string)
+    , _log_bitmask(log_bitmask)
+{
+    AP_Param::setup_object_defaults(this, var_info);
+    if (_instance != nullptr) {
+        AP_HAL::panic("DataFlash must be singleton");
+    }
+
+    _instance = this;
+}
+
 void DataFlash_Class::Init(const struct LogStructure *structures, uint8_t num_types)
 {
     gcs().send_text(MAV_SEVERITY_INFO, "Preparing log system");

libraries/DataFlash/DataFlash.h

@@ -50,22 +50,22 @@ class DataFlash_Class
 public:
     FUNCTOR_TYPEDEF(print_mode_fn, void, AP_HAL::BetterStream*, uint8_t);
     FUNCTOR_TYPEDEF(vehicle_startup_message_Log_Writer, void);
-    DataFlash_Class(const char *firmware_string, const AP_Int32 &log_bitmask) :
-        _firmware_string(firmware_string),
-        _log_bitmask(log_bitmask)
-        {
-            AP_Param::setup_object_defaults(this, var_info);
-            if (_instance != nullptr) {
-                AP_HAL::panic("DataFlash must be singleton");
-            }
-            _instance = this;
-        }
+
+    static DataFlash_Class create(const char *firmware_string, const AP_Int32 &log_bitmask) {
+        return DataFlash_Class{firmware_string, log_bitmask};
+    }
 
     // get singleton instance
     static DataFlash_Class *instance(void) {
         return _instance;
     }
-    
+
+    constexpr DataFlash_Class(DataFlash_Class &&other) = default;
+
+    /* Do not allow copies */
+    DataFlash_Class(const DataFlash_Class &other) = delete;
+    DataFlash_Class &operator=(const DataFlash_Class&) = delete;
+
     void set_mission(const AP_Mission *mission);
 
     // initialisation
@@ -222,6 +222,8 @@ protected:
                                bool is_critical);
 
 private:
+    DataFlash_Class(const char *firmware_string, const AP_Int32 &log_bitmask);
+
     #define DATAFLASH_MAX_BACKENDS 2
     uint8_t _next_backend;
     DataFlash_Backend *backends[DATAFLASH_MAX_BACKENDS];