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MTLogger

Multi-threaded safe, crossplatform logger for Lazarus/FPC and Delphi.

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README

MTLogger — thread-safe, cross-platform Logger for Lazarus/FPC and Delphi

MTLogger is a thread-safe, cross-platform logger for Lazarus/FPC and Delphi.
It supports asynchronous file logging, real-time log capture, and optional immediate console output.
MTLogger is implemented as a singleton, so no manual initialization is required.

Quickstart

  1. Download u_logger.pas or install MTLogger using the boss install command:
bash
boss install https://github.com/kompustelnik/MTLogger
  1. Add u_logger to the uses section:
pascal
uses
  u_logger;
  1. (OPTIONALLY) Assign OnLogEventProc (for global procedures) or OnLogEventObj (e.g. for class methods) to catch logs real-time.
pascal
procedure TForm1.FormCreate(Sender: TObject);
begin
  MTLogger.OnLogEventObj:= CatchLog;
  MTLogger.Log('Starting application.');
end;

procedure TForm1.CatchLog(const AMessage: String);
begin
  Memo1.Lines.Add(AMessage);
end;

With this setup, any log message generated via Log, LogWarning, or LogError can be captured in real-time.

  1. Start logging:
  • Info log:
pascal
MTLogger.Log('Hello, World!');
  • Warning log:
pascal
MTLogger.LogWarning('Settings file modified');
  • Error log:
pascal
MTLogger.LogError('Exception message: ' + E.Message);

Logging directly to the console

In console applications, you can print a log message immediately:

pascal
WriteLn(MTLogger.Log('Starting application'));

Example output:

pascal
2026-01-25 22:01:29 - INFO - Starting application.

Sample log file

pascal
2026-01-25 21:22:29 - INFO - Starting application.
2026-01-25 21:22:37 - INFO - Button 1 pressed
2026-01-25 21:22:38 - INFO - Checkbox 1 checked
2026-01-25 21:22:38 - INFO - Checkbox 2 checked
2026-01-25 21:22:49 - WARNING - Button 2 pressed
2026-01-25 21:22:49 - ERROR - Button 3 pressed
2026-01-25 21:22:50 - INFO - Button 1 pressed
2026-01-25 21:22:50 - INFO - Button 1 pressed
2026-01-25 21:22:51 - INFO - Closing application.

Features

  • Cross-platform support: Windows, Linux, macOS
  • Supports real-time capture via OnLogEventProc/OnLogEventObj
  • Can log INFO, WARNING, and ERROR levels
  • Safe shutdown, ensuring no log messages are lost
  • Optional immediate console output for console apps