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Single Responsibility Principle 단일 책임 원칙
-
Aclass should only have one reason to change
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Separation of concerns - different classes handling different, independent tasks/problems.
Open/Closed Principle 개방/폐쇄 원칙
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Classes should be open for extension but closed for modification
Liskov Substition Principle 리스코프 치환원칙
-
You should be able to substitute a base type for a subtype
Interface Segregation Principle 인터페이스 분리 원칙
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Don't put too much into an interface; split into separate interfaces
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YAGNI-You Ain't Going to Need It -> 필요할때구현, 예상으로 구현하지 말라. XP원칙DTSTTCPW(동작이 가능한 가장 단순한 것을 하라, do the simplest thing that could possibly work)
Dependency Inversion Principle 의존관계역전의 원칙
-
High-level modules should not depend upon low-level ones; use abstractions.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
namespace SOLID
{
#region SRP Single Responsibility Principle
public class Journal
{
private readonly List<string> entries = new List<string>();
public static int count = 0;
public int AddEntry(string Text)
{
entries.Add($"{++count} : {Text}");
return count;
}
public void RemoveEntry(int index)
{
entries.RemoveAt(index);
}
public override string ToString()
{
return string.Join(Environment.NewLine, entries);
}
// Save & Load Method는 entries 처리를 위한 기능들이 아님.
// Class의 관심사가 다름 SRP 분할 처리 하는게 좋음.
public void Save(string filename)
{
}
public void Load(string filename)
{
}
//
}
class Persistence
{
public void SaveToFile(Journal j, string filename, bool overwrite = false)
{
if (overwrite || !File.Exists(filename))
File.WriteAllText(filename, j.ToString());
}
}
#endregion SRP
#region OCP Open Close Principle
public enum Color
{
Red, Green, Blue
}
enum Size
{
Small, Medium, Large, Yuge
}
class Product
{
public string name;
public Color color;
public Size size;
public Product(string name, Color color, Size size)
{
if (name == null) throw new ArgumentNullException(paramName: nameof(name));
this.name = name;
this.color = color;
this.size = size;
}
}
class ProductFilter
{
public IEnumerable<Product> FilterBySize(IEnumerable<Product> products, Size size)
{
foreach (var p in products)
{
if (p.size == size) yield return p;
}
}
public IEnumerable<Product> FilterByColor(IEnumerable<Product> products, Color color)
{
return from p in products
where p.color == color
select p;
}
public IEnumerable<Product> FilterBySizeAbdColor(IEnumerable<Product> products, Size size, Color color)
{
return products.Where(p => p.color == color && p.size == size).Select(p => p);
}
}
public interface ISpecification<T>
{
bool IsSatisfied(T t);
}
public interface IFilter<T>
{
IEnumerable<T> Filter(IEnumerable<T> items, ISpecification<T> spec);
}
class ColorSpecification : ISpecification<Product>
{
Color color;
public ColorSpecification(Color color)
{
this.color = color;
}
public bool IsSatisfied(Product t)
{
return t.color == color;
}
}
class SizeSpecification : ISpecification<Product>
{
Size size;
public SizeSpecification(Size size) => this.size = size;
public bool IsSatisfied(Product t) => t.size == size;
}
class AndSpecification<T> : ISpecification<T>
{
ISpecification<T> first, second;
public AndSpecification(ISpecification<T> first, ISpecification<T> second)
{
if (first == null) throw new ArgumentNullException(paramName: nameof(first));
this.first = first;
this.second = second ?? throw new ArgumentNullException(paramName: nameof(second));
}
public bool IsSatisfied(T t)
{
return first.IsSatisfied(t) && second.IsSatisfied(t);
}
}
class BetterFilter : IFilter<Product>
{
public IEnumerable<Product> Filter(IEnumerable<Product> items, ISpecification<Product> spec)
{
foreach (var i in items)
if (spec.IsSatisfied(i))
yield return i;
}
}
#endregion OCP
#region LSP Liskov Substitution Principle
class Rectangle
{
public virtual int Width { get; set; }
public virtual int Height { get; set; }
public Rectangle(int width, int height)
{
Width = width;
Height = height;
}
public Rectangle()
{
}
public override string ToString()
{
return $"{nameof(Width)} : {Width}, {nameof(Height)} : {Height}";
}
}
class Square : Rectangle
{
public override int Width { set { base.Width = base.Height = value; } }
public override int Height { set => base.Width = base.Height = value; }
}
#endregion
#region ISP Interface Segregation Principle
class Document
{
}
interface IMachine
{
void print(Document d);
void scan(Document d);
void fax(Document d);
}
class MultifunctionPrinter : IMachine
{
public void fax(Document d) => throw new NotImplementedException();
public void print(Document d) => throw new NotImplementedException();
public void scan(Document d)
{
throw new NotImplementedException();
}
}
interface IPrinter
{
void Print(Document d);
}
interface IScanner
{
void Scan(Document d);
}
class Photocopier : IPrinter, IScanner
{
public void Print(Document d)
{
throw new NotImplementedException();
}
public void Scan(Document d)
{
throw new NotImplementedException();
}
}
interface IMultiFunctionDevice : IScanner,IPrinter//...
{
}
class MultifunctionDevice : IMultiFunctionDevice
{
IPrinter printer;
IScanner scanner;
public MultifunctionDevice(IPrinter printer, IScanner scanner)
{
this.printer = printer;
this.scanner = scanner;
}
public void Print(Document d)
{
printer.Print(d);
}
public void Scan(Document d)
{
scanner.Scan(d);
}//decorator pattern
}
#endregion
#region DIP Dependency Inversion Principle
enum Relationship
{
Parent, Child, Sibling
}
class Person
{
public string Name { get; set; }
}
interface IRelationshipBrowser
{
IEnumerable<Person> FindAllChildrenOf(string name);
}
class RelationshipsH : IRelationshipBrowser
{
public List<(Person, Relationship, Person)> Relations { get; } = new List<(Person, Relationship, Person)>();
public void AddParentAndChild(Person parent, Person child)
{
Relations.Add((parent, Relationship.Parent, child));
Relations.Add((child, Relationship.Child, parent));
}
public IEnumerable<Person> FindAllChildrenOf(string name)
{
//foreach (var r in Relations.Where(
// x => x.Item1.Name == name && x.Item2 == Relationship.Parent
// ))
//{
// yield return r.Item3;
//}
//return from r in Relations.Where(
// x => x.Item1.Name == name && x.Item2 == Relationship.Parent
// )
//select r.Item3;
return Relations.Where(
x => x.Item1.Name == name && x.Item2 == Relationship.Parent
).Select(r => r.Item3);
}
}
//low-level
class Relationships
{
public List<(Person, Relationship, Person)> Relations { get; } = new List<(Person, Relationship, Person)>();
public void AddParentAndChild(Person parent, Person child)
{
Relations.Add((parent, Relationship.Parent, child));
Relations.Add((child, Relationship.Child, parent));
}
}
class Research
{
public Research(Relationships relationships)
{
var relations = relationships.Relations;
foreach (var r in relations.Where(
x => x.Item1.Name == "John" && x.Item2 == Relationship.Parent
))
{
Console.WriteLine($"John has a child called {r.Item3.Name}");
}
}
public Research(IRelationshipBrowser browser)
{
foreach (var p in browser.FindAllChildrenOf("John"))
Console.WriteLine($"John has a child called {p.Name}");
}
}
#endregion
class Program
{
static public int Area(Rectangle r) => r.Width * r.Height;
static void Main(string[] args)
{
#region SRP Single Responsibility Principle
Journal j = new Journal();
j.AddEntry("Hello World!");
j.AddEntry("Hello World2!");
Persistence persistence = new Persistence();
string filename = @"c:\j.txt";
//persistence.SaveToFile(j, filename, true);
//Process.Start(filename);
#endregion SRP
#region OCP Open Close Principle
var apple = new Product("Apple", Color.Green, Size.Small);
var tree = new Product("Tree", Color.Green, Size.Large);
var house = new Product("House", Color.Blue, Size.Large);
List<Product> products = new List<Product> { apple, tree, house };
for (int i = 0; i < 10; i++)
{
products.Add(new Product(i.ToString(), Color.Green, Size.Large));
}
Stopwatch sw = new Stopwatch();
sw.Start();
//
var pf = new ProductFilter();
Console.WriteLine("Old Filter 시작 시간 : {0}", sw.Elapsed.Milliseconds.ToString());
Console.WriteLine("Green products (old):");
foreach (var p in pf.FilterByColor(products, Color.Green))
{
//Console.WriteLine($" - {p.name} {p.color} is green");
}
Console.WriteLine("Old Filter 종료 시간 : {0}", sw.Elapsed.Milliseconds.ToString());
//
var bF = new BetterFilter();
Console.WriteLine("New Filter 시작 시간 : {0}", sw.Elapsed.Milliseconds.ToString());
Console.WriteLine("Green products (new):");
foreach (var p in bF.Filter(products, new ColorSpecification(Color.Green)))
{
//Console.WriteLine($" - {p.name} {p.color} is green");
}
Console.WriteLine("New Color Filter 처리 시간 : {0}", sw.Elapsed.Milliseconds.ToString());
Console.WriteLine("Large products (new):");
foreach (var p in bF.Filter(products, new SizeSpecification(Size.Large)))
{
//Console.WriteLine($" - {p.name} {p.color} is green");
}
Console.WriteLine("New Size Filter 처리 시간 : {0}", sw.Elapsed.Milliseconds.ToString());
foreach (var p in bF.Filter(products,
new AndSpecification<Product>(
new ColorSpecification(Color.Green),
new SizeSpecification(Size.Large)
)))
{
}
sw.Stop();
#endregion OCP
#region LSP Liskov Substitution Principle
Rectangle rc = new Rectangle(3, 4);
Console.WriteLine($"{rc} has area {Area(rc)}");
Square sq = new Square();
sq.Width = 4;
Console.WriteLine($"{sq} has area {Area(sq)}");
Rectangle recsq = new Square();
recsq.Width = 4;
Console.WriteLine($"{recsq} has area {Area(recsq)}");
#endregion LSP
#region ISP Interface Segregation Principle
#endregion
#region DIP Dependency Inversion Principle
var parent = new Person { Name = "John" };
var child1 = new Person { Name = "Chris" };
var child2 = new Person { Name = "Mary" };
var relationships = new Relationships();
relationships.AddParentAndChild(parent, child1);
relationships.AddParentAndChild(parent, child2);
new Research(relationships);
var relationshipsH = new RelationshipsH();
relationshipsH.AddParentAndChild(parent, child1);
relationshipsH.AddParentAndChild(parent, child2);
new Research(relationshipsH);
#endregion
}
}
}
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