C# Language Pocket Reference

Attributes

Attributes are language constructs that can decorate a code element (assemblies, modules, types, members, return values, and parameters) with additional information.

In every language, you specify information associated with the types, methods, parameters, and other elements of your program. For example, a type can specify a list of interfaces from which it derives, or a parameter can specify modifiers, such as the ref modifier in C#. The limitation of this approach is that you can associate information with code elements using only the predefined constructs that the language provides.

Attributes allow programmers to extend the types of information associated with these code elements. For example, serialization in the .NET Framework uses various serialization attributes applied to types and fields to define how these code elements are serialized. This approach is more flexible than requiring the language to have special syntax for serialization.

Attribute Classes

An attribute is defined by a class that inherits (directly or indirectly) from the abstract class System.Attribute. When specifying an attribute to an element, the attribute name is the name of the type. By convention, the derived type name ends in Attribute, although specifying the suffix is not required when specifying the attribute.

In this example, the Foo class is specified as serializable using the Serializable attribute:

[Serializable]
public class Foo {...}

The Serializable attribute is actually a type ...