Builder

Step Builder: the builder enforces construction order.

#When to use it

When there are mandatory steps and order that the client cannot break.

public interface INeedHost { INeedPort WithHost(string host); }
public interface INeedPort { ICanBuild WithPort(int port); }
public interface ICanBuild { Connection Build(); }

public class ConnectionBuilder : INeedHost, INeedPort, ICanBuild
{
    private string _host = ""; private int _port;

    public static INeedHost Create() => new ConnectionBuilder();
    public INeedPort WithHost(string host) { _host = host; return this; }
    public ICanBuild WithPort(int port)    { _port = port; return this; }
    public Connection Build() => new(_host, _port);
}

// Forced usage:
var c = ConnectionBuilder.Create().WithHost("db").WithPort(5432).Build();

#creational #fluent #type-safe