fix SPDLOG-library related class

include/snipplib/utils/snplib_logger.h

@@ -81,6 +81,28 @@ public:
     constexpr static std::array LOGGER_DEFAULT_FORMAT = {std::string_view{"[%Y-%m-%d %T.%e]"}, std::string_view{"[%l]"},
                                                          std::string_view{": "}, std::string_view{"%v"}};
 
+    // special logger names
+
+    constexpr static std::string_view STDOUT_LOGGER_MARK{"stdout"};
+
+    constexpr static std::string_view STDERR_LOGGER_MARK{"stderr"};
+
+    constexpr static std::string_view NULL_LOGGER_MARK{"null"};
+
+    /*                          helper method                               */
+
+    static std::shared_ptr<spdlog::logger> makeLoggerFromMark(std::string const& mark, std::string const& name)
+    {
+        if (mark == STDOUT_LOGGER_MARK) {
+            return std::make_shared<spdlog::stdout_logger_mt>(name);
+        } else if (mark == STDERR_LOGGER_MARK) {
+            return std::make_shared<spdlog::stderr_logger_mt>(name);
+        } else if (mark == NULL_LOGGER_MARK) {
+            return std::make_shared<spdlog::null_logger_mt>(name);
+        } else {  // 'mark' is filename here
+            return std::make_shared<spdlog::basic_logger_mt>(name, mark);
+        }
+    }
 
     /*                          some factory static methods                          */
 
@@ -89,7 +111,7 @@ public:
     static snplib_spdlog_logger_t makeConsoleLogger(std::string const& logger_name,
                                                     R const& pattern_range = LOGGER_DEFAULT_FORMAT)
     {
-        return snplib_spdlog_logger_t(spdlog::stdout_logger_mt(logger_name), pattern_range);
+        return snplib_spdlog_logger_t(std::make_shared<spdlog::stdout_logger_mt>(logger_name), pattern_range);
     }
 
     template <std::ranges::input_range R = decltype(LOGGER_DEFAULT_FORMAT)>
@@ -97,7 +119,7 @@ public:
     static snplib_spdlog_logger_t makeConsoleErrLogger(std::string const& logger_name,
                                                        R const& pattern_range = LOGGER_DEFAULT_FORMAT)
     {
-        return snplib_spdlog_logger_t(spdlog::stderr_logger_mt(logger_name), pattern_range);
+        return snplib_spdlog_logger_t(std::make_shared<spdlog::stderr_logger_mt>(logger_name), pattern_range);
     }
 
 
@@ -105,7 +127,7 @@ public:
         requires snplib_input_char_range_c<std::ranges::range_value_t<R>>
     static snplib_spdlog_logger_t makeNullLogger(std::string const& logger_name)
     {
-        return snplib_spdlog_logger_t(spdlog::null_logger_mt(logger_name));
+        return snplib_spdlog_logger_t(std::make_shared<spdlog::null_logger_mt>(logger_name));
     }
 
 
@@ -132,6 +154,7 @@ public:
         _loggerSPtr->set_pattern(_currentLogPattern);
     }
 
+
     virtual ~snplib_spdlog_logger_t() = default;
 
     void setLoglevel(spdlog::level::level_enum level)