Log4mql(mini) MT4 - library for MetaTrader 4

Log4mql(mini) MT4 – library MetaTrader 4

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Log4mql(mini) – light header-only version of Log4mql that provides standardized logging.


Installation/Usage

  • Add log4mqlm.mqh to your Include folder.
  • View the sample code to get an overview of the usage.

    Inputs

    Log4mql(mini) requires only one input field. There is no logging to files.

    • Loglevel, supports Trace, Debug, Info, Warn, Error and Fatal

    Log4mql(mini) Inputs

      Message Pattern

      The message pattern will have a fixed format which corresponds to its appropriate severity level, according to below table.

       Severity Format
      		 Sample output
       Info (the commonly used default) %func: %msg
      		 OnInit:  Log level: TRACE
       Debug, Trace
      		 %func(%file:%line): %msg
      		 OnInit(log4mqlm_sample.mq4:72): initializing
       Warn
      		 WARN %func(%file:%line): %msg
      		WARN SomeFunction(log4mqlm_sample.mq4:64): stoploss too tight
       Error
      		 ERROR %func(%file:%line): %msg
      optionally followed by: [, error %lasterr – %lasterrdesc]      		 ERROR OnDeinit(log4mqlm_sample.mq4:85): open ‘some file’ failed,  error 5004 – Cannot open file
       Fatal FATAL … as above
      		 FATAL  …


      Functions

      Log4mql(mini) provides functions and preprocessor macros for logging, all macros are to be used like functions.

      Return type
      		Function name
      		Description
       bool
      		  PRINT (…)
      		  Prints its message if log level is set at least to INFO (= normal logging behavior).
       Supports up to 9 arguments – PRINT(“1”,2,etc) – if you need more, expand the templates.
       Returns true if message was logged, else false.
       bool
      		  PRINTF (string format,…)
      		  Like PRINT but prints a formatted message. Same rules as known from PrintFormat apply.
       bool
      		  WARN (…)
       WARNF (string format,…)
      		 Prints its message if log level is set at least to WARN.
       bool
      		  ERROR (…)
       ERRORF (string format,…)
      		 Prints its message if log level is at least ERROR. Adds _LastError description if set.
       bool
      		  FATAL (…)
       FATALF (string format,…)
      		 Like ERROR, but with termination. You should call ExpertRemove() or exit immediately otherwise after this.
       Example:
         if(step<MinStep) { FATALF(“invalid step size: %f”,step); ExpertRemove(); return; }
       bool
      		  DEBUG (…)
       DEBUGF (string format,…)
      		 Messages for DEBUG level.
       bool
      		  TRACE (…)
       TRACEF (string format,…)
      		 Messages for TRACE (more verbose than DEBUG, for function entries, calculations etc).



       string  L4mq.LastMessage()  Get the last message that has been logged.
       int  L4mq.LastLevel()  Get the severity level of the last logging event.
       int  L4mq.Level()  Get the severity level of the logger.
       string  L4mq.LevelAsString()  Get the severity level of the logger as string.
       void  L4mq.SetLevel(int)  Set the severity level for the logger.
       ulong  L4mq.SeqNr()  Get the sequence number of the last logged event.
       bool  L4mq.logged  true if the last event was logged.
           
       string  Log4mql::GetErrorDescription(int err)  Get the description of an error code like _LastError.
       string
      		  Log4mql::GetUninitReason(int reason)  Get the description of the uninit reason.
       string  Log4mql::LoglevelToString(int level)  Convert a log level to a descriptive string.
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      Notes

      • As the functionality strives to be as simple as possible, there is no logging to files. You could implement some on your own if you want.
      • You are free to use this code in your work, however, if you share the source code you must not remove the copyright and license notice.
      • The full functionality of Log4mql is available here: https://www.mql5.com/en/code/31425 (MT4) or here: https://www.mql5.com/en/code/31452 (MT5)
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      Log4mql(mini) MT4 – library MetaTrader 4
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