if Yes, why so? When an object of the class is returned by value. When an object of the class is passed (to a function) by value as an argument. Copy an object to pass it as an argument to a function. 3. 3. Assignment operator is declared as private. 4. Default and Copy constructors are declared as private. So the final solution would be: The copy constructor and the copy assignment operator should be declared private, i.e. 2. In C++, a Copy Constructor may be called in following cases: 1. The change in C++11 has forced compilers to implement the construction of local static variables (like INSTANCE) in a thread-safe manner.. For this to qualify as Singleton you could make class Wibble's constructor private (and make theWibble a static member function). Thread safety. To prevent outside source from creating (or copying) an instance of our singleton class, we need to shield the constructor and copy constructor of the singleton class. 2. NhÆ° vậy class Singleton đã trông gọn hÆ¡n nhiều, và chỉ khi hàm getInstance() được gọi thì một instance mới được khởi tạo. The copy constructor is a constructor which creates an object by initializing it with an object of the same class, which has been created previously. The copy is the type of constructor which is used to create a copy of the already existing object of the class type. Phillip_msdn wrote: > I ve a doubt. Singleton class requires below methods and variables. LÆ°u ý instance này sẽ chỉ được khởi tạo 1 lần duy nhất, và việc khởi tạo này cÅ©ng là thread safe kể từ C++11. The copy constructor is an overloaded constructor used to declare and initialize an object from another object.. C++ Copy Constructor. When is copy constructor called? Accessing the singleton is thread-safe. Private singleton constructor and copy Constructor: Singleton class should not allow users to create singleton instances but they should request class to return an instance. The copy constructor is used to − Initialize one object from another of the same type. C++ Singleton the right way. Have a static function that will return the pointer to the class. If you are using C++ 11, you may leave the copy constructor and the copy assignment operator public but explicitly delete them: public: When an object is constructed based on another object of the same class. C++ - Singleton Class. Is it necessary to override copy constructor inside a sigleton class? private: Singleton(const Singleton&); Singleton& operator=(const Singleton&); Otherwise, you will be able to clone your object. What's more, in C++ you can actually store the static instance variable within the getInstance() function. preface In the web related problems, from the input URL to the entire page loading and display to the user, this problem is inseparable, it mainly involves two steps: network request and client rendering Network request DNS resolution TCP connection establishment SSL / TLS tunnel establishment (HTTPS) Send HTTP request Return HTTP message Disconnect SSL […] About method and variables for Designing Singleton class in C++ . This is a so-called "magic static", otherwise known as a "Meyers Singleton", and since C++11 it guarantees you get thread-safe construction of the singleton object. 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