Dernière version du 7 juin 2020 à 15:31

Description

Compose objects into tree structures to represent part-whole hierarchies.
Composite lets clients treat individual objects and compositions of objects uniformly

Treat single objects and composite objects in the same way
Arrange structured hierarchies so that single components and groups of components can be treated in the same way

Exemple

IComponent.cs

public interface IComponent
{
    string Name { get; set; }
    void Add(IComponent component);
    void Remove(IComponent component);
    string Display(int depth);
    IComponent Find(string name);
    void AddSuffix(string suffix);
}

User.cs

public class User : IComponent
{
    public string Name { get; set; }

    public User(string name)
    {
        this.Name = name;
    }

    public void Add(IComponent component)
    {
        throw new NotSupportedException("Cannot add a component to a user.");
    }

    public void Remove(IComponent component)
    {
    }

    public string Display(int depth) => $"{new String('-', depth)} {Name}\n";

    public IComponent Find(string name) => name.Equals(this.Name) ? this : null;

    public void AddSuffix(string suffix)
    {
        Name += suffix;
    }
}

UsersGroup.cs

public class UsersGroup : IComponent
{
    public string Name { get; set; }
    ICollection<IComponent> components;

    public UsersGroup(string name)
    {
        this.components = new List<IComponent>();
        this.Name = name;
    }

    public void Add(IComponent component)
    {
        components.Add(component);
    }

    public void Remove(IComponent componentToRemove)
    {
        if (!components.Remove(componentToRemove))
        {
            foreach (var component in components)
            {
                component.Remove(componentToRemove);
            }
        }
    }

    public string Display(int depth)
    {
        var stringBuilder = new StringBuilder();
        stringBuilder.AppendLine($"{new String('-', depth)} {Name}");

        foreach (var component in components)
        {
            stringBuilder.Append(component.Display(depth + 1));
        }

        return stringBuilder.ToString();
    }

    public IComponent Find(string name)
    {
        if (name.Equals(this.Name))
            return this;

        foreach (var component in components)
        {
            var matchingComponent = component.Find(name);
            if (matchingComponent != null)
                return matchingComponent;
        }

        return null;
    }

    public void AddSuffix(string suffix)
    {
        Name += suffix;
        foreach (var component in components)
        {
            component.AddSuffix(suffix);
        }
    }
}

var group1 = new UsersGroup("Group1");
var user1 = new User("Nicolas");
group1.Add(user1);
var user2 = new User("Guillaume");
group1.Add(user2);

var group2 = new UsersGroup("Group2");
var user3 = new User("Paul");
group2.Add(user3);
var user4 = new User("Marie");
group2.Add(user4);

var group = new UsersGroup("Group");
group.Add(group1);
group.Add(group2);
var user5 = new User("Jean");
group.Add(user5);

group.AddSuffix("!");

group.Remove(group.Find("Guillaume"));
group.Remove(group.Find("Group2"));

Console.WriteLine(group.Display(1));