Question

Suppose i’m writing a software that it has about 50 classes.
We can divide classes into 2 part:
1. classes we forced to create instance for more that of once instance.
2. classes we just create a one instance until end of program.

So, suppose i have MainProgram class and everything do here, then just
make an instance in main.cpp and run my program.
Now, I need to pass instances created just once (option 2) to other classes, Do you
have any idea to implement to this?
Because i can’t new again. i just work with old instance.For example:
I wrote a SocketNetwork Class that its constructor get port number and bind to it.
So i can’t rebind again and i forced to access to resoures of the given port number.

Answer 1

Seems like you’re looking for the singleton pattern.

It goes something like:

class A
{
public:
   static A& getInstance()
   {
      static A a;
      return a;
   }
private:
   A() {}
};

Because the constructor is private, you can only get the single instance of A that is created through the getInstance() method, which you can call anywhere.

`A::getInstance()`

will always return the same instance of A.