Design Patterns

Creational Design Patterns

Singleton

Ensure a class only has one instance, and provide a global point of access to it.

Implementation

• The class is made responsible for its own instance
• It intercepts the call for construction and returns a single instance
• Same instance is returned every time
• Therefore, direct construction of objects is disabled
• The class creates its own instance which is provided to the clients

Simple Implementation

velocity.h

#ifndef VELOCITY_H
#define VELOCITY_H

class Velocity
{
    Velocity() = default;
    static Velocity m_Instance;
public:
    static Velocity & Instance();
    void MethodA();
    void MethodB();
};

#endif // VELOCITY_H

velocity.cpp

#include "velocity.h"

Velocity Velocity::m_Instance;

Velocity& Velocity::Instance()
{
    return m_Instance;
}

void Velocity::MethodA()
{

}

void Velocity::MethodB()
{

}