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| Ligne 7 : | Ligne 7 : | ||
= Example = | = Example = | ||
<filebox fn='User.cs'> | <filebox fn='User.cs'> | ||
public class User | public class User | ||
{ | { | ||
public string Name { get; set; } | public string Name { get; set; } | ||
| Ligne 40 : | Ligne 40 : | ||
} | } | ||
public void Visit( | public void Visit(User user) | ||
{ | { | ||
user.Name += $" ({this.Title})"; | |||
} | } | ||
} | } | ||
Dernière version du 3 avril 2022 à 20:47
Description
Allow adding new behaviors to existing class hierarchy without altering existing code.
This pattern is particularly useful when, you cannot modify existing classes but need to add new features.
Example
| User.cs |
public class User
{
public string Name { get; set; }
public User(string name)
{
this.Name = name;
}
public void Accept(IVisitor visitor)
{
visitor.Visit(this);
}
}
|
| IVisitor.cs |
public interface IVisitor
{
void Visit(User user);
}
|
| TitleVisitor.cs |
public class TitleVisitor : IVisitor
{
public string Title { get; set; }
public TitleVisitor(string title)
{
this.Title = title;
}
public void Visit(User user)
{
user.Name += $" ({this.Title})";
}
}
|
|
var user = new User("Nicolas");
Console.WriteLine(user.Name); // Nicolas
user.Accept(new TitleVisitor("Boss"));
Console.WriteLine(user.Name); // Nicolas (Big Boss)
|
