🪵 Modular Configurable Logging Framework (C++)

A reusable C++11 logging library demonstrating Encapsulation, Inheritance, Polymorphism, Abstraction, Composition.

✨ Features

• 6 levels: TRACE, DEBUG, INFO, WARNING, ERROR, FATAL
• Multiple outputs: console + file
• Timestamped records (YYYY-MM-DD HH:MM:SS)
• Configurable threshold filtering
• Extensible formatter/handler design

🏗️ Architecture

┌─────────────────────────────────────┐
│     Application Code (Your App)     │
└──────────────┬──────────────────────┘
               │ uses
               ↓
┌─────────────────────────────────────┐
│    Logger (Core Coordinator)        │  ← Composition
└──────────────┬──────────────────────┘
               │ delegates to
       ┌───────┴────────┐
       ↓                ↓
┌─────────────┐  ┌──────────────┐
│  Formatter  │  │ Log Handlers │  ← Polymorphism
│ (Strategy)  │  │   (Outputs)  │
└─────────────┘  └──────┬───────┘
                        │
           ┌────────────┴────────────┐
           ↓                         ↓
    ┌─────────────┐          ┌─────────────┐
    │   Console   │          │    File     │
    │   Handler   │          │   Handler   │
    └─────────────┘          └─────────────┘

🔐 Important OOP Concepts

• Encapsulation: internal file/stream state hidden inside handlers
• Inheritance: ConsoleHandler / FileHandler derive from LogHandler
• Polymorphism: shared write() interface for all handlers
• Abstraction: Formatter and LogHandler are abstract interfaces
• Composition: Logger owns formatter + list of handlers

🚀 Quick Start

#include "Logger.h"
#include "SimpleFormatter.h"
#include "ConsoleHandler.h"
#include "FileHandler.h"

int main() {
    SimpleFormatter fmt;
    Logger logger(LogLevel::INFO, &fmt);

    ConsoleHandler console;
    FileHandler file("logs/app.log");
    logger.addHandler(&console);
    logger.addHandler(&file);

    logger.info("Application started");
    logger.error("Something went wrong");
    return 0;
}

⚙️ Build

Windows (MinGW)

g++ -std=c++11 -I include main.cpp src/*.cpp -o logging_demo.exe

Linux/macOS

g++ -std=c++11 -I include main.cpp src/*.cpp -o logging_demo
./logging_demo

📁 Structure

include/: LogLevel, LogRecord, Formatter, SimpleFormatter, LogHandler, ConsoleHandler, FileHandler, Logger
src/:     LogRecord.cpp, SimpleFormatter.cpp, ConsoleHandler.cpp, FileHandler.cpp, Logger.cpp
main.cpp: demo app
logs/:    runtime log output

📌 Key API

• Logger(LogLevel level, Formatter* fmt)
• addHandler(LogHandler* handler)
• log(level, message) + trace/debug/info/warning/error/fatal

✅ Notes

• C++11 compatible (GCC/Clang/MSVC)
• Easy to extend with JSON formatter, rotating file handler, async logging, thread safety