Write a program to show the singleton pattern used in python.

Answer

Singleton patter is used to provide a mechanism that limits the number of instances that can be used by one class. It also allows the same object to be shared between many different parts of the code. This allows the global variables to be used as the actual data that is used is hidden by the singleton class interface. The singleton class interface can have only one public member and one class method Handle. Private constructors are not used to create an object that is used outside the class. The process waits for the static member function to create new instances and return the singleton object. The code that is used to call the singleton object is:

Singleton& Singleton::Handle()
{
if( !psingle ) {
psingle = new Singleton;
}
return *psingle;
}