Page 143 - CSharp/C#

Chapter 16: Attributes

Examples

Creating a custom attribute

//1) All attributes should be inherited from System.Attribute
//2) You can customize your attribute usage (e.g. place restrictions) by using
System.AttributeUsage Attribute
//3) You can use this attribute only via reflection in the way it is supposed to be used
//4) MethodMetadataAttribute is just a name. You can use it without "Attribute" postfix - e.g.
[MethodMetadata("This text could be retrieved via reflection")].
//5) You can overload an attribute constructors
[System.AttributeUsage(System.AttributeTargets.Method | System.AttributeTargets.Class)]
public class MethodMetadataAttribute : System.Attribute
{
//this is custom field given just for an example
//you can create attribute without any fields
//even an empty attribute can be used - as marker
public string Text { get; set; }

//this constructor could be used as [MethodMetadata]
public MethodMetadataAttribute ()
{
}

//This constructor could be used as [MethodMetadata("String")]
public MethodMetadataAttribute (string text)
{
Text = text;
}
}

Using an attribute

[StackDemo(Text = "Hello, World!")]
public class MyClass
{
[StackDemo("Hello, World!")]
static void MyMethod()
{
}
}

Reading an attribute

Method GetCustomAttributes returns an array of custom attributes applied to the member. After
retrieving this array you can search for one or more specific attributes.

var attribute = typeof(MyClass).GetCustomAttributes().OfType<MyCustomAttribute>().Single();

Or iterate through them

https://riptutorial.com/ 89