How to use Logger

The logging system in Kratos has 3 important parts:

• LoggerMessage a data class storing the message with some attributes like label, category, severity
• Logger is a singleton object in charge of gathering all messages produced in the code and passing them to the outputs
• LoggerOutput takes message and write it to the output (or file). This is the extension point of the logger and one can create its output to write only some messages (filtering by category, severity, label, etc.) with custom format.

Sending a Message

The simplest way to send a message is to use predefined macros:

KRATOS_INFO("Some label") << "Some message with value: " << 3.14 << " with more message";

This example sends a message with INFO severity and STATUS category. One can change the category by passing it to the message:

KRATOS_INFO("Number of Iterations") << number_of_iterations << LoggerMessage::Category::STATISTICS;