Chained builder pattern

CSharp · Console

/Program.cs

using System;

public class Program
{
	public static void Main()
	{
		var theThingTrue = new BuilderFoo().BuildFooTrue()
			.WithSomePropertyOnlyForTrue("face").Build();
		//var theThingTrueCompilerError = new BuilderFoo().BuildFooTrue().WithB(5).Build(); // compiler error
	
		var theThingFalse = new BuilderFoo().BuildFooFalse()
			.WithB(5).Build();
		//var theThingFalseCompilerError = new BuilderFoo().BuildFooFalse().WithSomePropertyOnlyForTrue("face").Build(); // compiler error
		
		Console.WriteLine("hello");
	}
}

	public interface ISettings
	{
		string SomePropertyOnlyForTrue { get; }
		int B { get; }
	}

	public class Settings : ISettings
	{
		public string SomePropertyOnlyForTrue { get; }
		public int B { get; }
		
		public Settings(string somePropertyOnlyForTrue)
		{
			SomePropertyOnlyForTrue = somePropertyOnlyForTrue;
		}
		
		public Settings(int b)
		{
			B = b;
		}
	}

	
	public interface IBuilderFoo
	{
		IBuilderFooTrue BuildFooTrue();
		IBuilderFooFalse BuildFooFalse();
	}

	public class BuilderFoo : IBuilderFoo
	{
		public IBuilderFooTrue BuildFooTrue()
		{
			return new BuilderFooTrue();
		}
		
		public IBuilderFooFalse BuildFooFalse()
		{
			return new BuilderFooFalse();
		}
	}
	

	public interface IBuilderFooTrue
	{
		IBuilderFooTrue WithSomePropertyOnlyForTrue(string value);
		ISettings Build();
	}

	public class BuilderFooTrue : IBuilderFooTrue
	{
		private string _somePropertyOnlyForTrue = string.Empty;
		
		public IBuilderFooTrue WithSomePropertyOnlyForTrue(string value)
		{
			_somePropertyOnlyForTrue = value;
			return this;
		}
		
		public ISettings Build()
		{
			return new Settings(_somePropertyOnlyForTrue);
		}
	}
	

	public interface IBuilderFooFalse
	{
		IBuilderFooFalse WithB(int value);
		ISettings Build();
	}

	public class BuilderFooFalse : IBuilderFooFalse
	{
		private int _b;
		
		public IBuilderFooFalse WithB(int value)
		{
			_b = value;
			return this;
		}
		
		public ISettings Build()
		{
			return new Settings(_b);
		}
	}