- "Narrow Change Strategy"   -> Schnittstellenumbau
        public string GetErrorMessage()
        {
            return this.errorMessage;
        }



Narrow change: use an existing variable, to assign it something new (ie. the change we want to apply in several places),
and then to inline that variable, so that our change takes effect everywhere where the variable was used.
http://dwyler.net/blog/refactoring-introduce-new-class-and-move-behaviour-to-it/


- "Feature Envy"  Circle.toString()

-
		public override bool Contains(int x, int y)
		{
			int squaredDistanceToCenter = sqrd(x, this.x) + sqrd(y, this.y);

			bool result = squaredDistanceToCenter <= Math.Sqrt(radius);

			if (result)
			{
				numberOfContainingPoints++;
			}
			return result;
		}


--------------
mit Point


		public override bool Contains(Point point)
		{
			int squaredDistanceToCenter = sqrd(point.X, this.x) + sqrd(point.Y, this.y);

			bool result = squaredDistanceToCenter <= Math.Sqrt(radius);

			if (result)
			{
				numberOfContainingPoints++;
			}
			return result;
		}

		private int sqrd(int a, int b)
		{
			return (a - b) * (a - b);
		}


		public int CountContainingPoints(int[] xCords, int[] yCords)
		{
			Point[] points = new Point[xCords.Length];

			for (int i = 0; i < points.Length; ++i)
			{
				points[i] = new Point(xCords[i], yCords[i]);

			}

			return CountContainingPoints(points);
		}

		public int CountContainingPoints(Point[] points)
		{
			numberOfContainingPoints = 0;
			for (int i = 0; i < points.Length; ++i)
			{
				Contains(points[i]);
			}
			return numberOfContainingPoints;
		}


----------------
		public override bool Contains(Point point)
		{
			bool result = point.SquaredDistanceToCenter(this.x, this.y) <= Math.Sqrt(radius);

			if (result)
			{
				numberOfContainingPoints++;
			}
			return result;
		}

		public int SquaredDistanceToCenter(int x, int y)
		{
			return (this.X - x) * (this.X - x) + (this.Y - y) * (this.Y - y);
		}




------------------


		[TestMethod]
		public void LISKOV_BREAK()
		{
			Square square = GetCustomShape(  );
			   // new Rectangle(widht =3, height = 4);

			square.Width = 2;


			Assert.AreEqual(4, square.CalculateArea());
			--> 8 as Area

		}





---------------------
Simulated Polymorphic Behaviour
-
		public override string ToXml()
		{
			StringBuilder builder = new StringBuilder();
			builder.Append("<circle");
			builder.Append(" x=\"" + this.X + "\"");
			builder.Append(" y=\"" + this.Y + "\"");
			builder.Append(" radius=\"" + this.GetRadius() + "\"");
			builder.Append(" />\n");

			return builder.ToString();
		}


		public abstract string ToXml();

		//public virtual string ToXml()
		//{
		//	StringBuilder builder = new StringBuilder();

		//	builder.Append(ToXml());

		//	return builder.ToString();
		//}



-------- Int to Enum --------
Intro new class SystemStateNew (not enum)
 new property NewState { get; set; }

Add more code that assigns state

Goal:
            SystemStateNew stateNew = SystemStateNew.AllServicesOK;


Assert.Equal(SystemStateNew.AllServicesOK, stateNew);



Assert.Equal("All Services OK", SystemState.GetDescriptionForState(SystemState.AllServicesOK));



Assert.Equal("All Services OK", SystemStateNew.GetDescriptionForState(SystemStateNew.AllServicesOK));




-----------------

The Core 6 refactorings are:

* Rename
* Inline

* Extract Method

* Introduce Local Variable

* Introduce Parameter

* Introduce Field




In typical OO languages, there are 4 things we can name:

1. local variables,

2. methods,

3. parameters,

4. fields.


There are also classes, but those are different.
I think of variables, methods, parameters, and fields as scalars.
They are atomic, simple things. Classes are compositions; they compose scalars together.



http://arlobelshee.com/the-core-6-refactorings/
--> Let me repeat that: if you find yourself typing indentation, newlines, space around parens, or anything else like that, you are wasting your time.



Your editor may manipulate text better than an IDE. It may start up faster. But it can’t manipulate code as quickly as an IDE.




---
todos

-
Focus on 5-8 Resharper Shortcuts only
  -> See Evernote

Use this as progress during the class
[ ] is TODO, [X] is done

TODO
[X] "Complicated Boolean"
    Circle.Contains
       bool result = (x - this.x) * (x - this.x) +
                     (y - this.y) * (y - this.y) <=
                          radius * radius;
		int squaredDistanceToCenter = sqrd(x, this.x) + sqrd(y, this.y);
			bool result = squaredDistanceToCenter <= Math.Sqrt(radius);


[X] ShapeGroup.Add
      --> Long Method
        Extract till you drop


[X] Ctrl E, H -> View Hierarchy
   SimpleShape  Collapse hierarchy -> Alt+Del
    Show visual

[X] DrawingBoard: Remove inheritance

[X] Speculative Generality ComplexShape
   Pull Members Up + Delete class


[X] Remove IShape -> not needed
   * "Convert interface to abstract class"
   * Move all members up (instead of down)
   * Alt+Del (Collapse hierarchy)


[X] "Refused Bequest"  Square+Rectangle
    1st show "Alternative class different interface"                           <--------------
    Remove unused "ContainsLine" and "GetHeight"
    Encapsulate field: public int GetX() {


[X] Color.GetColorFormatted
      --> Flag Parameter
          Extract, Gradual Cutover
[X] 2. Flag Parameter smell in constructor
   public FileWriter(string newContent, bool useAppendMode)
		Create 2 classes: AppendingFileWriter, OverwritingFileWriter
		Extract method "virtual WriteToFile"    -> if (isInAppendMode)
		Move code from FileWriter to the 2 classes
		Use "Replace Constructor with Factory Method"
		Create instance of AppendingFileWriter if isAppending

    Template method: Additional.FileWriter


[X] Inappropriate Intimacy

[X] ShapeGroup.shapes[]
      --> Parallel Change
	     What is public?
		 Encapsulate field -> don't update local usages.
		 Write Access first
		 Encapsulate "size"
		 Read Access second
https://martinfowler.com/bliki/ParallelChange.html


[X] Primitive Obsession x,y -> Point


[X] "Duplicated Code"
       Pull Up color from Rec+Circle

[X] "Alternative classes with diff interface"
       contains / containsPoint()

[X] "Inconsistent solution":
      ToString()


[X] Color.ErrorCode -> Exception
[X] "Data Clump"
[X] "Feature Envy"  Circle.toString()
   Access circle.  multiple times


[X] Int to Enum
  -> Gradual cutover


[ ] Refactoring: "Convert to Indexer"



[X] "Primitive Obsession"
 Circle WriteXml(StringBuilder builder)
 {
   builder.Append("<circle");
   builder.Append(" x=\"" + GetX() + "\"");
   builder.Append(" y=\"" + GetY() + "\"");
   builder.Append(" radius=\"" + GetRadius() + "\"");

Introduce:
	//   using System.Xml.Linq;
	var xmlElement = new XElement("circle",
		 new XAttribute("x", circle.GetX()),
		 new XAttribute("y", circle.GetY()),
		 new XAttribute("radius", circle.GetRadius()));
	return xmlElement.ToString();

[ ] AbstractShape.ToXML
      --> Switch to Polymorphism
        StringBuilder before and return after
		Extract, Make Static,
        Move Method, Make Non-Static,
        PullUp Method
    2: Visitor Pattern:
Use no return value in Visitor --> but property string XmlString.

		1. Add IShapeVisitor  that can visit different shapes
		2. Add the Accept(IShapeVisitor v) on every shape by starting on "abstract class Shape"
		3. Implement a ShapeToXmlConverter
		4. Move code from ToXml to ShapeToXmlConverter (don't inline *all*)
		5. Fix square   Accept & GetHeight to play well
		6. Use visitor to traverse and get XML
              var converter = new ShapeToXmlConverter();
              return (string)this.Accept(converter);

	ADVANCED: Make Generic VisitorReturns<string>

[ ] PersonNameStrategy
    Transform Parameters
	  Select 3 parameters
	  PersonNameStrategy


------------
# URL to Source
http://bit.ly/QbtYzJ


#Tips
  Collapse hierarchy = Alt+Del on class

## 2: Visitor Pattern:
		1. Add IShapeVisitor  that can visit different shapes
		2. Add the Accept(IShapeVisitor v) on every shape
		3. Implement a ShapeToXmlConverter
		4. Move code from ToXml to ShapeToXmlConverter
		5. Fix square   Accept & GetHeight to play well
		6. Use visitor to traverse and get XML

	Additional.zip

## Flag Parameter smell in constructor
   public FileWriter(string newContent, bool useAppendMode)

	Create 2 classes: AppendingFileWriter, OverwritingFileWriter
	Extract method "virtual WriteToFile"    -> if (isInAppendMode)
	Move code from FileWriter to the 2 classes
	Use "Replace Constructor with Factory Method"
	Create instance of AppendingFileWriter if isAppending


## x,y --> Point
     Tricky: CountContainingPoints(
                int[] xCords, int[] yCords)

## shapes[] "Encapsulate field"
## shapes[] --> List<IShape> shapeList

# Align interfaces: contains / containsPoint

# Inconsistent solution toString()

# Find an get rid of dead code

# Primitive Obsession in "writing XML"
    --> Use "System.Xml.Linq.XElement"

# Circle.ToString   Feature Envy



# Links



# Tips Naming
* The names indicates exactly, what the variable/method/class/package is intended for.
* Every variable/method/class/package only does, what its name suggests.
* Assess the quality of names from the callers perspective (on the declaration side, they always seem clear).
* Let others assess the quality of names (e.g. in a code review).