single-responsibility-principle.md

Single Responsibility Principle

Robert C. "Unle Bob" Martin saying is Each software module should have one and only one reason to change.

According to Wikipedia; The Single Responsibility Principle states that every object shoul have a single responsiblity, and that responsibility should be entirely encapsulated by class

Do one thing Do that thing only Do that thing well

• STRIVE FOR low coupling and high cohesion!
• Follow Iterface Segregation Principle (ISP) can helpt to achieve Single Responsibility principle

It is not fulfill with the SRP. It is doing two things namely. Greeting the user if they can join, or rejecting them if they cannot.

public void UserJoin(User user)
{
    if (verify.CanJoin(user))
    {
        messages.Greeting(user);
    }
    else
    {
        this.kick(user);
    }
}

It might be better to reorganize the method

public void UserJoin(User user)
{
  user.CanJoin ? GreetUser(user) : RejectUser(user);
}

public void Greetuser(User user)
{
  messages.Greeting(user);
}

public void RejectUser(User user)
{
  messages.Reject(user);
  this.kick(user);
}

One more example that is class based

Bad design

public class Order
{
    public void SaveOrder()
	{
		// runs
	}
	public void SaveAddress()
	{
		// runs
	}
	public void SendNotification()
	{
		// runs
	}
}

This should be more cleaner and understandable for sure

public class Order
{
    public void SaveOrder()
	{
		// runs
	}
}

public class Address
{
    public void SaveAdress()
	{
		// runs
	}
}

public class Notification
{
    public void SendNotification()
	{
		// runs
	}
}