logger

Logging

LOG(LogLevel level, std::string prefix)

Built-in logging functionality has been provided to aid debugging. To use the logger, you must include the Logger.h header file. std::cout statements should be generally avoided. The LOG(level, prefix) macro should be used for all logging/debugging needs. The LOG macro uses the Logger class to provide this functionality. The Logger class should generally not be accessed directly. The macro returns a string stream object that can be used exactly as std::cout for printing output. Streamed in content is flushed to stdout as soon as execution passes beyond the terminating semi-colon of the log statement.

A brief description of when to use which log level is given with the LogLevel enum doxygen documentation. The following is a summary:

• LEV_ERROR: Use for errors that require model code or input file modification/fixing (use extremely sparingly)
• LEV_WARN: Use to report questionable simulation state (use extremely sparingly)
• LEV_INFO1: Information helpful for simulation users and developers alike - least verbose.
• LEV_INFO[2, 3, 4]
• LEV_INFO5: Information helpful for simulation users and developers alike - most verbose.
• LEV_DEBUG1: debugging information - least verbose
• LEV_DEBUG[2, 3, 4]
• LEV_DEBUG5: debugging information - most verbose

Developers working on agents set the LOG prefix argument to a unique archetype/agent-specific identifier (up to 6 characters long). This will allow developers to more easily filter the logger output in order to isolate information most relevant to their work.

This macro does a check on the given LogLevel 'level' argument; if the specified level is not higher than or equal to the report-level cutoff, the macro does nothing, limiting the performance impact of logging statements.

Warning

Do NOT place any state-changing expressions with the LOG macro as they may not run if the report level excludes the specified LogLevel.

Note

The Python interface should use the Python standard library logging system.

Examples

#include "Logger.h"

void myfunc() {

  LOG(LEV_ERROR, "prefix") << "This is my error statement. "
                           << "and more info...";

  LOG(LEV_DEBUG2, "prefix") << "This is my first debug statement. "
                            << "and more info...";
  LOG(LEV_DEBUG1, "prefix") << "This is another debug statement. "
                            << "and more info...";
}

The command-line specified verbosity is used to determine the logger report-cutoff. Available levels are described in the LogLevel enum. In the above example if the command line verbosity were set to LEV_DEBUG1, the first and third statements would print, while the second would not. Output would be something like this:

ERROR (prefix): This is my error statement. and more info...
DEBUG1(prefix): This is another debug statement. and more info...

Any expression placed with a log statement that is not printed will not be executed. An example of what NOT to do follows:

LOG(LEV_DEBUG2, "module name") << "The expression myobject.setName(newname): "
                               << myobject.setName(newname)
                               << " might not ever execute"
                               << " depending on the verbosity level.";