state & strategy

Author: T0shik

README.md

@@ -32,3 +32,6 @@ Full Playlist can be found [here](https://www.youtube.com/playlist?list=PLOeFnOV
 - [Mediator](https://youtu.be/VYLD75sU1rw)
 - [Memento](https://youtu.be/SAaIsErpGDY)
 - [Observer](https://youtu.be/8nICu7ZSPtE)
+- [Strategy](https://youtu.be/25qf3VkAlis)
+- [State](https://youtu.be/rYmVpqiGL14)
+

state/example.linq

@@ -0,0 +1,65 @@
+<Query Kind="Program" />
+
+void Main()
+{
+
+}
+
+public partial class Computer
+{
+	private State _state = new Off();
+
+	private void SetState(State state)
+	{
+		_state = state;
+	}
+
+	public void PressPowerButton()
+	{
+		_state.PressPowerButton(this);
+	}
+}
+
+public partial class Computer
+{
+	private interface State
+	{
+		void PressPowerButton(Computer computer);
+	}
+
+	private class Off : State
+	{
+		public void PressPowerButton(Computer computer)
+		{
+			// perform some work
+			computer.SetState(new On());
+		}
+	}
+
+	private class On : State
+	{
+		private bool charging;
+		
+		public void PressPowerButton(Computer computer)
+		{
+			// perform some work
+			if (charging)
+			{
+				computer.SetState(new Standby());
+			}
+			else
+			{
+				computer.SetState(new Off());
+			}
+		}
+	}
+
+	private class Standby : State
+	{
+		public void PressPowerButton(Computer computer)
+		{
+			// perform some work
+			computer.SetState(new On());
+		}
+	}
+}

state/real_use_case.linq

@@ -0,0 +1,66 @@
+<Query Kind="Program" />
+
+void Main()
+{
+
+}
+
+public partial class Pen
+{
+	private State _state = new Idle();
+
+	private void SetState(State state) => _state = state;
+
+	public void OnClick(Pen pen) => _state.OnClick(this);
+
+	public void OnClickFinish(Pen pen) => _state.OnClickFinish(this);
+
+	public void OnMove(Pen pen) => _state.OnMove(this);
+}
+
+public partial class Pen
+{
+	private interface State
+	{
+		void OnMove(Pen pen);
+		void OnClick(Pen pen);
+		void OnClickFinish(Pen pen);
+	}
+
+	private class Idle : State
+	{
+		public void OnClick(Pen pen)
+		{
+			pen.SetState(new Writing());
+		}
+
+		public void OnClickFinish(Pen pen)
+		{
+			// do nothing
+		}
+
+		public void OnMove(Pen pen)
+		{
+			// do nothing
+		}
+	}
+
+	private class Writing : State
+	{
+		public void OnClick(Pen pen)
+		{
+			// DRAW HARDER
+		}
+
+		public void OnClickFinish(Pen pen)
+		{
+			pen.SetState(new Idle());
+		}
+
+		public void OnMove(Pen pen)
+		{
+			// draw on canvas
+		}
+	}
+
+}

state/the_mess.linq

@@ -0,0 +1,42 @@
+<Query Kind="Program" />
+
+void Main()
+{
+
+}
+
+public class Computer
+{
+	private int state = 0;
+	private bool charging = true;
+
+	public void PressPowerButton()
+	{
+		// off
+		if (state == 0)
+		{
+			// do work
+			state = 1;
+			return;
+		}
+		
+		// on
+		if (state == 1)
+		{
+			// do work
+			if (charging)
+			{
+				state = 2;
+				return;
+			}
+			state = 0;
+			return;
+		}
+		
+		// standby
+		// do work
+		state = 1;
+	}
+}
+
+

strategy/composable.linq

@@ -0,0 +1,64 @@
+<Query Kind="Program" />
+
+void Main()
+{
+	var chain1 = new Log().Append(new Transaction()).Append(new Add(5));
+	chain1.Do(10);
+
+	"-------------------".Dump();
+
+	var chain2 = new Log().Append(new Add(10)).Append(new Transaction());
+	chain2.Do(10);
+}
+
+public abstract class Strategy{
+	
+	private Strategy _next;
+	
+	public Strategy Append(Strategy next) {
+		if(_next == null){
+			_next = next;
+		} else {
+			_next.Append(next);
+		}
+		
+		return this;
+	}
+
+	public abstract void Do(int n);
+	
+	protected void Next(int n) => _next?.Do(n);
+}
+
+public class Log : Strategy
+{
+	public override void Do(int n)
+	{
+		n.Dump("Logging number:");
+		Next(n);
+	}
+}
+
+public class Transaction : Strategy
+{
+	public override void Do(int n)
+	{
+		n.Dump("Starting Transaction");
+		Next(n);
+		n.Dump("Finishing Transaction");
+	}
+}
+
+public class Add : Strategy
+{
+	int _num;
+	public Add(int num) => _num = num;
+	
+	public override void Do(int n)
+	{
+		n.Dump($"Adding {_num} to {n}");
+		int result = n += _num;
+		n.Dump($"Result: {result}");
+		Next(result);
+	}
+}

strategy/example.linq

@@ -0,0 +1,58 @@
+<Query Kind="Program" />
+
+void Main()
+{
+	
+}
+
+public class FileController
+{
+	IFileStorage filestorage;
+	public FileController(IFileStorage filestorage) => this.filestorage = filestorage;
+}
+
+
+public interface IFileStorage
+{
+	byte[] GetFile(string id);
+	void SaveFile();
+}
+
+public class Local : IFileStorage
+{
+	public byte[] GetFile(string id)
+	{
+		throw new NotImplementedException();
+	}
+
+	public void SaveFile()
+	{
+		throw new NotImplementedException();
+	}
+}
+
+public class S3 : IFileStorage
+{
+	public byte[] GetFile(string id)
+	{
+		throw new NotImplementedException();
+	}
+
+	public void SaveFile()
+	{
+		throw new NotImplementedException();
+	}
+}
+
+public class Bespoke : IFileStorage
+{
+	public byte[] GetFile(string id)
+	{
+		throw new NotImplementedException();
+	}
+
+	public void SaveFile()
+	{
+		throw new NotImplementedException();
+	}
+}

strategy/generic.linq

@@ -0,0 +1,26 @@
+<Query Kind="Program" />
+
+void Main()
+{
+	new Thing<A>().Do();
+	new Thing<B>().Do();
+}
+
+public class Thing<T> where T : class, IStrategy, new()
+{	
+	public void Do() => new T().Do();
+}
+
+public interface IStrategy {
+	void Do();
+}
+
+public class A : IStrategy
+{
+	public void Do() => "a".Dump();
+}
+
+public class B : IStrategy
+{
+	public void Do() => "b".Dump();
+}

strategy/single_function.linq

@@ -0,0 +1,14 @@
+<Query Kind="Program" />
+
+void Main()
+{
+	var process = new Process();
+	process.Setup(p =>
+	{
+		// ad hoc strategy
+	});
+}
+
+public class Process {
+	public void Setup(Action<Process> setup) => setup(this);
+}