C++ Singleton design pattern

Question

C++ Singleton design pattern

As of late, I've chanced upon an acknowledgement/execution of the Singleton configuration design for C++. It has resembled this (I have embraced it from the genuine model):

// a lot of methods are omitted here

class Singleton

{

   public:

       static Singleton getInstance( );

       ~Singleton( );

   private:

       Singleton( );

       static Singleton instance;

};

From this declaration, I can deduce that the instance field is initiated on the heap. That means there is a memory allocation. What is completely unclear for me is when exactly the memory is going to be deallocated? Or is there a bug and memory leak? It seems like there is a problem with the implementation.
My fundamental inquiry is, how would I carry out it in the correct manner?

singleton design-pattern cpp

4 years ago by vishaljlf39

2 Answers

Login / Signup to Answer the Question.

Login Signup

**espadacoder11** · Answer 1 · 2021-05-17T10:20:21

You could avoid memory allocation. There are many variants, all having problems in case of multithreading environment.

I prefer this kind of implementation (actually, it is not correctly said I prefer, because I avoid singletons as much as possible):



class Singleton

{

private:

   Singleton();



public:

   static Singleton& instance()

   {

      static Singleton INSTANCE;

      return INSTANCE;

   }

};

It has no dynamic memory allocation.

**kshitijrana14** · Answer 2 · 2021-05-18T11:50:48

Another non-allocating alternative: create a singleton, say of class C, as you need it:

singleton<C>()

using

template <class X>

X& singleton()

{

    static X x;

    return x;

}

C TUTORIAL

C PROGRAMS

INTERVIEW TESTS

EXECUTE CODE

C++ TUTORIAL

C++ PROGRAMS

INTERVIEW TESTS

EXECUTE CODE

PYTHON TUTORIAL

PYTHON HOW TOS

INTERVIEW TESTS

EXECUTE CODE

JAVA TUTORIAL

JAVA CODE EXAMPLES

SPRING TUTORIAL

MORE IN JAVA

COMPUTER ARCHITECTURE

COMPUTER NETWORK

OPERATING SYSTEM

DBMS & SQL

PL/SQL

MongoDB

EXECUTE SQL

ANDROID DEVELOPMENT

GO LANGUAGE

LINUX

DOCKER

HTML TAGS (A to Z)

CSS REFERENCES

SASS/SCSS

KOTLIN

GAME DEVELOPMENT

PHP

GIT GUIDE

JAVASCRIPT

ADVANCED DSA

C++ Singleton design pattern

2 Answers

Login / Signup to Answer the Question.