Logging library for mql4 – library MetaTrader 4

This is a logging library to quickly add logging capabilities to your code without  much hassle. The library’s default behavior matches most cases however most of the functionality can be customized using pre-processor substitutions (#define)

See the example scripts on how to use library.

How to use

#include <Logger.mqh>

//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
   DEBUG("This id debug");
   INFO("This is info");
   ERROR("This is an error");
  }
//+------------------------------------------------------------------+

Customization notes

• The logger uses following format to print logs

// [time, except LOGGER_PRINT,LOGGER_ALERT] [level] [prefix] [message] [last error, only Logger::Error]

#define LOGGER_PRINT    1     // print to log
#define LOGGER_ALERT    2     // trigger alert
#define LOGGER_FILE     4     // write to a file
#define LOGGER_NOTIFY   8     // send a notification

example:

#define LOGGER_SET_DEBUG 0       // DEBUG is disabled
#define LOGGER_SET_INFO  1|2     // Print and alert
#define LOGGER_SET_ERROR 1|2|4   // Print, alert and file write 

• Customize the prefix section as follows

#define LOGGER_PREFIX __FILE__ + " | Line:" + IntegerToString(__LINE__) // [filename] | [Line number]

• Customize file name by a string constant or a function call

#define LOGGER_FILENAME "backtest_debug.log"
// or
#define LOGGER_FILENAME IntegerToString(AccountNumber())

Notes:

• #define before the Logger.mqh is included.
• To disable a logger level set the level as zero.
• LOGGER_NOTIFY and LOGGER_FILE execution errors are handled as a print statements. Do not customize it to use library’s own error handling, the program might trigger an infinite loop or a stack overflow.