Providing logging macro signature that accepts std::string (#573)

* Providing logging macro signature that accepts std::string

* - RCLCPP_ prefix to macros Add
- New tests added

* - Added doc to the functions and macros
- Functions declared as RCLCPP_PUBLIC

* - Small typo in doc corrected

* Fixed error when compiling with clang

* touch up docs

rclcpp/include/rclcpp/utilities.hpp

@@ -210,6 +210,26 @@ sub_will_underflow(const T x, const T y)
   return (y > 0) && (x < (std::numeric_limits<T>::min() + y));
 }
 
+/// Return the given string.
+/**
+ * This function is overloaded to transform any string to C-style string.
+ *
+ * \param[in] string_in is the string to be returned
+ * \return the given string
+ */
+RCLCPP_PUBLIC
+const char *
+get_c_string(const char * string_in);
+
+/// Return the C string from the given std::string.
+/**
+ * \param[in] string_in is a std::string
+ * \return the C string from the std::string
+ */
+RCLCPP_PUBLIC
+const char *
+get_c_string(const std::string & string_in);
+
 }  // namespace rclcpp
 
 #endif  // RCLCPP__UTILITIES_HPP_

rclcpp/resource/logging.hpp.em

@@ -21,6 +21,7 @@
 
 #include "rclcpp/logger.hpp"
 #include "rcutils/logging_macros.h"
+#include "rclcpp/utilities.hpp"
 
 // These are used for compiling out logging macros lower than a minimum severity.
 #define RCLCPP_LOG_MIN_SEVERITY_DEBUG 0
@@ -30,6 +31,9 @@
 #define RCLCPP_LOG_MIN_SEVERITY_FATAL 4
 #define RCLCPP_LOG_MIN_SEVERITY_NONE 5
 
+#define RCLCPP_FIRST_ARG(N, ...) N
+#define RCLCPP_ALL_BUT_FIRST_ARGS(N, ...) __VA_ARGS__
+
 /**
  * \def RCLCPP_LOG_MIN_SEVERITY
  * Define RCLCPP_LOG_MIN_SEVERITY=RCLCPP_LOG_MIN_SEVERITY_[DEBUG|INFO|WARN|ERROR|FATAL]
@@ -82,7 +86,8 @@ def is_supported_feature_combination(feature_combination):
 @[ for param_name, doc_line in feature_combinations[feature_combination].params.items()]@
  * \param @(param_name) @(doc_line)
 @[ end for]@
- * \param ... The format string, followed by the variable arguments for the format string
+ * \param ... The format string, followed by the variable arguments for the format string.
+ * It also accepts a single argument of type std::string.
  */
 #define RCLCPP_@(severity)@(suffix)(logger, @(''.join([p + ', ' for p in get_macro_parameters(feature_combination).keys()]))...) \
   static_assert( \
@@ -94,7 +99,8 @@ def is_supported_feature_combination(feature_combination):
 @(''.join(['    ' + p + ', \\\n' for p in params]))@
 @[ end if]@
     logger.get_name(), \
-    __VA_ARGS__)
+    rclcpp::get_c_string(RCLCPP_FIRST_ARG(__VA_ARGS__, "")), \
+      RCLCPP_ALL_BUT_FIRST_ARGS(__VA_ARGS__,""))
 
 @[ end for]@
 #endif

rclcpp/src/rclcpp/utilities.cpp

@@ -353,3 +353,15 @@ rclcpp::sleep_for(const std::chrono::nanoseconds & nanoseconds)
   // Return true if the timeout elapsed successfully, otherwise false.
   return !g_is_interrupted;
 }
+
+const char *
+rclcpp::get_c_string(const char * string_in)
+{
+  return string_in;
+}
+
+const char *
+rclcpp::get_c_string(const std::string & string_in)
+{
+  return string_in.c_str();
+}

rclcpp/test/test_logging.cpp

@@ -92,6 +92,26 @@ TEST_F(TestLoggingMacros, test_logging_named) {
   EXPECT_EQ("message 3", g_last_log_event.message);
 }
 
+TEST_F(TestLoggingMacros, test_logging_string) {
+  for (std::string i : {"one", "two", "three"}) {
+    RCLCPP_DEBUG(g_logger, "message " + i);
+  }
+  EXPECT_EQ(3u, g_log_calls);
+  EXPECT_EQ("message three", g_last_log_event.message);
+
+  RCLCPP_DEBUG(g_logger, "message " "four");
+  EXPECT_EQ("message four", g_last_log_event.message);
+
+  RCLCPP_DEBUG(g_logger, std::string("message " "five"));
+  EXPECT_EQ("message five", g_last_log_event.message);
+
+  RCLCPP_DEBUG(g_logger, std::string("message %s"), "six");
+  EXPECT_EQ("message six", g_last_log_event.message);
+
+  RCLCPP_DEBUG(g_logger, "message seven");
+  EXPECT_EQ("message seven", g_last_log_event.message);
+}
+
 TEST_F(TestLoggingMacros, test_logging_once) {
   for (int i : {1, 2, 3}) {
     RCLCPP_INFO_ONCE(g_logger, "message %d", i);