added context light copy

Author: sy-c

include/InfoLogger/InfoLogger.hxx

@@ -80,6 +80,12 @@ class InfoLoggerContext final
   /// \param listOfKeyValuePairs      A list of fieldName / value pairs to be set. Fields which were set automatically from environment are overwritten.
   InfoLoggerContext(const std::list<std::pair<FieldName, const std::string&>>& listOfKeyValuePairs);
 
+  /// Create new context.
+  /// The context is created as a copy of an existing context.
+  /// Additionnaly, listed fields are set with provided value.
+  /// \param listOfKeyValuePairs      A list of fieldName / value pairs to be set. Fields which were set from copy source are overwritten.
+  InfoLoggerContext(const InfoLoggerContext &sourceContext, const std::list<std::pair<FieldName, const std::string&>>& listOfKeyValuePairs);
+
   /// Update context with default values
   /// All fields are cleared with default values.
   void reset();

src/InfoLoggerContext.cxx

@@ -30,6 +30,23 @@ InfoLoggerContext::InfoLoggerContext(const std::list<std::pair<FieldName, const
   setField(listOfKeyValuePairs);
 }
 
+InfoLoggerContext::InfoLoggerContext(const InfoLoggerContext &sourceContext, const std::list<std::pair<FieldName, const std::string&>>& listOfKeyValuePairs)
+{
+  // members initialization from source context
+  facility = sourceContext.facility;
+  role = sourceContext.role;
+  system = sourceContext.system;
+  detector = sourceContext.detector;
+  partition = sourceContext.partition;
+  run = sourceContext.run;
+  processId = sourceContext.processId;
+  hostName = sourceContext.hostName;
+  userName = sourceContext.userName;
+
+  // now set fields provided as arguments
+  setField(listOfKeyValuePairs);
+}
+
 InfoLoggerContext::~InfoLoggerContext()
 {
 }

test/testInfoLogger.cxx

@@ -48,6 +48,14 @@ int main()
   theLog.log({ InfoLogger::Severity::Info, 123, 456, __FILE__, __LINE__ }, "infoLogger message test with source code info");
   theLog.log(LOGINFO(123), "infoLogger message test with source code info");
 
+  // example use of context
+  InfoLoggerContext ctxt({{InfoLoggerContext::FieldName::Facility, std::string("test1")}});
+  theLog.log({{}},ctxt,"infoLogger message - facility test1");
+
+  // reuse a context and overwrite some fields
+  theLog.log({{}},InfoLoggerContext(ctxt,{{InfoLoggerContext::FieldName::Facility, std::string("test2")}}),"infoLogger message - facility test2");
+
+  // c++ style
   theLog << "another test message " << InfoLogger::endm;
   theLog << InfoLogger::Severity::Error << "another (stream error) message " << InfoLogger::endm;
   theLog << InfoLogger::Severity::Warning << "another (stream warning) message " << InfoLogger::endm;