Master Software Design Patterns and Architecture in C++/

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Singleton Pattern Implementation

Singleton Pattern Implementation

Learn about the singleton pattern through coding examples.

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Example one: simple implementation

Here’s an example of the singleton pattern implementation in C++.

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#include <iostream>
class MySingleton{
  private:
    static MySingleton* instance;
    MySingleton()= default;
    ~MySingleton()= default;
  public:
    MySingleton(const MySingleton&)= delete;
    MySingleton& operator=(const MySingleton&)= delete;
    static MySingleton* getInstance(){
      if ( !instance ){
        instance= new MySingleton();
      }
      return instance;
    }
};
MySingleton* MySingleton::instance= nullptr;
int main(){
  std::cout << '\n';
  std::cout << "MySingleton::getInstance(): "<< MySingleton::getInstance() << '\n';
  std::cout << "MySingleton::getInstance(): "<< MySingleton::getInstance() << '\n';
  std::cout << '\n';
}

Code explanation

  • Line 3: We created the MySingleton class.

  • Lines 5–8: We declared a private static MySingleton, which will store the object of the class alongside a private constructor and destructor.

  • Lines 11–12: We deleted the copy constructor and assignment operator so that our instance can’t be copied. ...