Custom attribute is used to record information irrelevant to the object in this province.

I thought of a simple example. This is an example of adding people as friends.

By default, A and B are friends. If B is enthusiastic or prefers to make friends, A will automatically add A friend. If B doesn't like making friends too much, then B will be one-way.

These habits actually have nothing to do with the object. in C #, additional information can be recorded through Attrubute (feature.

Here is a piece of code.

1. Define attributes

Namespace Test
{

[AttributeUsage (AttributeTargets. Class)]
Public class extends ricattribute: System. Attribute
{
Public parameter ricattribute ()
{

}
}

}

2. Define type

Public class Person
{
Private string m_Name;
Private Person m_person;


Public Person (string name)
{
This. m_Name = name;
}


Public virtual Person Friend
{
Get
{
If (m_person! = Null)
{
Return m_person;
}
Else
{
Return new Person ("NoFriend ");
}
}
Set
{
M_person = value;
// Append a friend
Response ricattribute att = System. Attribute. GetCustomAttribute (value. GetType (), typeof (Response ricattribute) as response ricattribute;
If (att! = Null)
{
Value. Friend = this;
}
}
}

Public override string ToString ()
{
Return this. m_Name;
}

}

 
[Symmetric]
Public class SpecialPerson: Person
{
Public SpecialPerson (string name): base (name)
{
}
}

Call:

Person c = new Person ("Person ");
SpecialPerson p = new SpecialPerson ("Person B ");
C. Friend = p;

Console. WriteLine (p. Friend. ToString ());
Console. WriteLine (c. Friend. ToString ());

P is more enthusiastic, so they will be friends with each other.