RAII(Resource Acquisition Is Initialization)

Resource acquisition is initialization (RAII) is a programming idiom used in several object-oriented languages to describe a particular language behavior.

RAII (Resource Acquisition Is Initialization) is one of the famous design patterns.

The technique was developed for exception-safe resource management in C++ during 1984–89, primarily by Bjarne Stroustrup and Andrew Koenig.

RAII patterns are important techniques for preventing leakage in languages such as C++ that require developers to directly manage resources.

Example (https://en.wikipedia.org/wiki/Resource_acquisition_is_initialization)

The following C++11 example demonstrates usage of RAII for file access and mutex locking:

#include <fstream>

#include <iostream>

#include <mutex>

#include <stdexcept>

#include <string>

void WriteToFile(const std::string& message) {

  // |mutex| is to protect access to |file| (which is shared across threads).

  static std::mutex mutex;

// Lock |mutex| before accessing |file|.

  std::lock_guard<std::mutex> lock(mutex);

// Try to open file.

  std::ofstream file("example.txt");

  if (!file.is_open()) {

    throw std::runtime_error("unable to open file");

  }

// Write |message| to |file|.

  file << message << std::endl;

// |file| will be closed first when leaving scope (regardless of exception)

  // mutex will be unlocked second (from lock destructor) when leaving scope

  // (regardless of exception).

}

<Ref : https://en.wikipedia.org/wiki/Resource_acquisition_is_initialization>

#RAII #Resource Acquisition Is Initialization #C++ #mutex #Memory leakage #std::auto_ptr