SOLID重點複習-2.LSP Liskov替換原則

using System;
					
public class Program
{
	public struct Point
	{
		public double x;
		public double y;
	}
	
	public class Shape
	{
		public Shape(string shapeName)
		{
			ShapeName = shapeName;
		}
		
		public string ShapeName;
		
		public static void DrawShape(Shape t)
		{
			if (t.ShapeName == "circle")
			{
				((Circle)t).Draw();
			}
		    if (t.ShapeName == "square")
			{
				(t as Square).Draw();
			}
		}
	}
	
	
	
	public class Circle : Shape
	{
		public Point center;
		public double radius;
		
		public Circle(string typeName):base(typeName)
		{
		}
		
		public void Draw()
		{
			Console.WriteLine("this is circle");
		}
	}
	
	public class Square : Shape
	{
		public Point TopLeft;
		public double side;
		public Square(string typeName):base(typeName)
		{
		}
		
		public void Draw()
		{
			Console.WriteLine("this is square");
		}
	}
	
	
	
	public static void Main()
	{
		//註：這邊更好是用列舉的方式指定Name, 強制約定
		Shape a = new Circle("circle");
		Shape b = new Square("square");
		
		Shape.DrawShape(a);
		Shape.DrawShape(b);
	}
}

using System;
					
public class Program
{
	public class Rectangle
	{
		protected double width;
		protected double height;
		public virtual double Height
		{
			get
			{
				return height;
			}
			
			set
			{
				height = value;
			}
		}
	
		public virtual double Width
		{
			get
			{
				return width;
			}
			
			set
			{
				width = value;
			}
		}
		
		public double Area()
		{
			return width*height;
		}
	}
	
	public class Square :Rectangle
	{
		public override double Height
		{
			get
			{
				return base.height;
			}
			
			set
			{
				base.width = value;
				base.height = value;
			}
		}
	
		public override double Width
		{
			get
			{
				return base.width;
			}
			
			set
			{
				base.height = value;
				base.width = value;
			}
		}
	}
	
	
	public static void Main()
	{
		Rectangle r = new Square();
		r.Width = 5; 
		r.Height = 4;
		//對正方向設定5再設定4的邊界，行為意圖比較像是拉動邊的長短而己
		Console.WriteLine("square area is "+r.Area());
		
		
	}
}

Rectangle r = new Square();
    var result = CalculateArea(r);

	public static double CalculateArea(Rectangle r)
	{
		r.Width = 4;
		r.Height = 5;
		
		if (r.Area() != 20)
			throw new Exception("bad area");
		
		return r.Area();
	}