visitor & template method

Author: T0shik

README.md

@@ -34,4 +34,6 @@ Full Playlist can be found [here](https://www.youtube.com/playlist?list=PLOeFnOV
 - [Observer](https://youtu.be/8nICu7ZSPtE)
 - [Strategy](https://youtu.be/25qf3VkAlis)
 - [State](https://youtu.be/rYmVpqiGL14)
+- [Visitor](https://youtu.be/6SByyc-0c0s)
+- [Template Method](https://youtu.be/mcc4XQHpVC8)
 

template method/avoid.linq

@@ -0,0 +1,60 @@
+<Query Kind="Program" />
+
+void Main()
+{
+}
+
+public class Process
+{
+	public void Start()
+	{
+		A();
+		B();
+		C();
+	}
+
+	public void A() => "".Dump();
+	public void B() => "".Dump();
+	public void C() => "".Dump();
+}
+
+public class Process_Configured
+{
+	// more state === harder to understand
+	public void Start(int a)
+	{
+		A();
+		B();
+		if (a == 0)
+		{
+			C();
+		}
+		else
+		{
+			D();
+		}
+	}
+
+	public void A() => "".Dump();
+	public void B() => "".Dump();
+	public void C() => "".Dump();
+	public void D() => "".Dump();
+}
+
+
+public class Process_Strategy
+{
+	// use strategy to supply the algorithm, DO NOT vary it
+	Action strategy;
+	public Process_Strategy(Action strategy) => this.strategy = strategy;
+	
+	public void Start()
+	{
+		A();
+		B();
+		strategy();
+	}
+
+	public void A() => "".Dump();
+	public void B() => "".Dump();
+}

template method/example.linq

@@ -0,0 +1,44 @@
+<Query Kind="Program" />
+
+void Main()
+{
+	new Process().Start();
+	"--".Dump();
+	new Variation1().Start();
+	"--".Dump();
+	new Variation2().Start();
+	"--".Dump();
+	new Variation3().Start();
+}
+
+public class Process
+{
+	// template method
+	public void Start()
+	{
+		Step1();
+		Step2();
+		Step3();
+	}
+
+	protected virtual void Step1() => "Step 1".Dump();
+	protected virtual void Step2() => "Step 2".Dump();
+	protected virtual void Step3() => "Step 3".Dump();
+}
+
+public class Variation1 : Process
+{
+	protected override void Step1() => "Step 1 Adapted".Dump();
+}
+
+public class Variation2 : Process
+{
+	protected override void Step3() => "Step 3 Adapted".Dump();
+}
+
+public class Variation3 : Process
+{
+	protected override void Step1() => "Step 1 Mega Adapted".Dump();
+
+	protected override void Step2() => "Step 2 Adapted".Dump();
+}

template method/factory.linq

@@ -0,0 +1,36 @@
+<Query Kind="Program" />
+
+void Main()
+{
+	new Variation1().Start();
+	"--".Dump();
+	new Variation2().Start();
+	"--".Dump();
+	new Variation3().Start();
+}
+
+public abstract class Process
+{
+	public void Start()
+	{
+		var word = FactoryMethod();
+		// do something with word
+	}
+
+	protected abstract string FactoryMethod();
+}
+
+public class Variation1 : Process
+{
+	protected override string FactoryMethod() => "FactoryMethod Variation1".Dump();
+}
+
+public class Variation2 : Process
+{
+	protected override string FactoryMethod() => "FactoryMethod Variation2".Dump();
+}
+
+public class Variation3 : Process
+{
+	protected override string FactoryMethod() => "FactoryMethod Variation3".Dump();
+}

template method/hook.linq

@@ -0,0 +1,36 @@
+<Query Kind="Program" />
+
+void Main()
+{
+}
+
+public abstract class Process
+{
+
+	public void Start()
+	{
+		AbstractHook();
+		DefaultHook();
+	}
+	
+	public abstract void AbstractHook();
+	
+	public virtual void DefaultHook() {
+		// default func
+	}
+
+}
+
+public class A : Process
+{
+	public override void AbstractHook()
+	{
+		// override
+	}
+	
+	public override void DefaultHook() {
+		// prepend
+		base.DefaultHook();
+		// extend
+	}
+}

visitor/example.linq

@@ -0,0 +1,47 @@
+<Query Kind="Program" />
+
+void Main()
+{
+	
+}
+
+public abstract class Place
+{
+	public abstract void Visit(Visitor visitor);	
+}
+
+public abstract class Visitor
+{
+	public abstract void VisitPark(Park park);
+	public abstract void VisitHome(Home park);
+}
+
+public class Park : Place
+{
+	public override void Visit(Visitor visitor)
+	{
+		visitor.VisitPark(this);  
+	}
+}
+
+public class Home : Place
+{
+	public override void Visit(Visitor visitor)
+	{
+		visitor.VisitHome(this);
+	}
+}
+
+public class Dude : Visitor
+{
+	public override void VisitHome(Home park) => "play video games".Dump();
+
+	public override void VisitPark(Park park) => "smoke weed".Dump();
+}
+
+public class Robber : Visitor
+{
+	public override void VisitHome(Home park) => "steal some socks".Dump();
+
+	public override void VisitPark(Park park) => "steal a dog".Dump();
+}

visitor/the_mess.linq

@@ -0,0 +1,86 @@
+<Query Kind="Program" />
+
+void Main()
+{
+
+}
+
+
+// other types? == more repos? generic repos?...
+public interface IRepository
+{
+	int Get();
+	int[] List();
+	void Write(int id);
+	void Update(int id);
+}
+
+public class Postgresql : IRepository
+{
+	
+	public int Get()
+	{
+		throw new NotImplementedException();
+	}
+
+	public int[] List()
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Update(int id)
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Write(int id)
+	{
+		throw new NotImplementedException();
+	}
+}
+
+public class MongoDb : IRepository
+{
+	public int Get()
+	{
+		throw new NotImplementedException();
+	}
+
+	public int[] List()
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Update(int id)
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Write(int id)
+	{
+		throw new NotImplementedException();
+	}
+}
+
+public class Redis : IRepository
+{
+	public int Get()
+	{
+		throw new NotImplementedException();
+	}
+
+	public int[] List()
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Update(int id)
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Write(int id)
+	{
+		throw new NotImplementedException();
+	}
+}