組合模式 - Composite Pattern

用途

將對象”組合”成樹結構以表示部分-整體層次結構

classDiagram
  Client ..> Leaf
  Client ..> Composite
  Leaf --|> Component
  Composite --|> Component
  Composite "1" o--> "0..*" Component
  namespace CompositePattern {
    class Component{
      <<Abstract>>
      +Operation()*
    }
    class Leaf{
      +Operation()
    }
    class Composite{
      -List<Component> members
      +Operation()
      +Add(Component)
      +Remove(Component)
      +GetChild() 
    }
  }
  class Client{
    +Operation()
  }

例子

當談到組合模式（Composite Pattern）時，我們可以以一個組織架構為例來解釋

想像一個組織，它由多個部門組成，每個部門又可以進一步分為多個小組或子部門，而這些小組或子部門又可以進一步包含更小的單位或成員
整個組織結構形成了一個階層結構

在組織架構中，每個部門或單位都具有相似的屬性和行為，無論是部門還是小組，都有負責特定任務的成員
這種階層結構和相似的屬性和行為可以使用組合模式來設計和實現

Component

// 組織成員抽象類別
public abstract class OrganizationMember
{
    protected string name;

    public OrganizationMember(string name)
    {
        this.name = name;
    }

    public abstract void DisplayMemberInfo();
}

Leaf

// 部門類別，同時也是葉子節點
public class Department : OrganizationMember
{
    public Department(string name) : base(name)
    {
    }

    public override void DisplayMemberInfo()
    {
        Console.WriteLine("Department: " + name);
    }
}

Composite

// 組織類別，同時也是容器節點
public class Organization : OrganizationMember
{
    private List<OrganizationMember> members = new List<OrganizationMember>();

    public Organization(string name) : base(name)
    {
    }

    public void AddMember(OrganizationMember member)
    {
        members.Add(member);
    }

    public void RemoveMember(OrganizationMember member)
    {
        members.Remove(member);
    }

    public override void DisplayMemberInfo()
    {
        Console.WriteLine("Organization: " + name);

        foreach (var member in members)
        {
            member.DisplayMemberInfo();
        }
    }
}

Client

// 建立組織架構
Organization organization = new Organization("ABC Company");

Department salesDepartment = new Department("Sales Department");
Department marketingDepartment = new Department("Marketing Department");

Department developmentDepartment = new Department("Development Department");
Department qaDepartment = new Department("QA Department");

Department customerServiceDepartment = new Department("Customer Service Department");

organization.AddMember(salesDepartment);
organization.AddMember(marketingDepartment);

organization.AddMember(developmentDepartment);
organization.AddMember(qaDepartment);

organization.AddMember(customerServiceDepartment);

// 顯示組織架構
organization.DisplayMemberInfo();

Console.ReadLine();

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