How does inheritance work for Attributes?

What does the Inherited bool property on attributes refers to?

Does it mean that if I define my class with an attribute AbcAtribute (that has Inherited = true), and if I inherit another class from that class, that the derived class will also have that same attribute applied to it?

To clarify this question with a code example, imagine the following:

[AttributeUsage(AttributeTargets.Class, Inherited = true)]
public class Random: Attribute
{ /* attribute logic here */ }


[Random]
class Mother
{ }


class Child : Mother
{ }

Does Child also have the Random attribute applied to it?

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Yes that is precisely what it means. Attribute

[AttributeUsage(Inherited=true)]
public class FooAttribute : System.Attribute
{
private string name;


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


public override string ToString() { return this.name; }
}


[Foo("hello")]
public class BaseClass {}


public class SubClass : BaseClass {}


// outputs "hello"
Console.WriteLine(typeof(SubClass).GetCustomAttributes(true).First());
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最佳答案

When Inherited = true (which is the default) it means that the attribute you are creating can be inherited by sub-classes of the class decorated by the attribute.

So - if you create MyUberAttribute with [AttributeUsage (Inherited = true)]

[AttributeUsage (Inherited = True)]
MyUberAttribute : Attribute
{
string _SpecialName;
public string SpecialName
{
get { return _SpecialName; }
set { _SpecialName = value; }
}
}

Then use the Attribute by decorating a super-class...

[MyUberAttribute(SpecialName = "Bob")]
class MySuperClass
{
public void DoInterestingStuf () { ... }
}

If we create an sub-class of MySuperClass it will have this attribute...

class MySubClass : MySuperClass
{
...
}

Then instantiate an instance of MySubClass...

MySubClass MySubClassInstance = new MySubClass();

Then test to see if it has the attribute...

MySubClassInstance <--- now has the MyUberAttribute with "Bob" as the SpecialName value.

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Attribute inheritance is enabled by default.

You can change this behavior by:

[AttributeUsage (Inherited = False)]

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