Attributes (C# Programming Guide)

Attributes provide a powerful method of associating declarative information with C# code (types, methods, properties, and so forth). After an attribute is associated with a program entity, the attribute can be queried at run time by using a technique called reflection. For more information, see Reflection (C# Programming Guide).

Attributes occur in two forms:

• Attributes that are defined in the common language runtime (CLR).

• Custom attributes that you can create, to add extra information to your code. This information can later be retrieved programmatically.

In this example, the TypeAttributes.Serializable attribute is used to apply a specific characteristic to a class:

[System.Serializable]
public class SampleClass
{
    // Objects of this type can be serialized.
}

Attribute Overview

Attributes have the following properties:

• Attributes add metadata to your program. Metadata is information about the types defined in a program. All .NET assemblies contain a specified set of metadata that describe the types and type members defined in the assembly. You can add custom attributes to specify any additional information that is required.

• Your program can examine its own metadata or the metadata in other programs by using reflection. For more information, see Accessing Attributes With Reflection (C# Programming Guide).

• Attributes such as MarshallAsare used extensively in COM interop scenarios. For more information, see System.Runtime.InteropServices.MarshalAsAttribute and System.Runtime.InteropServices.StructLayoutAttribute.

Related Sections

For more information, see:

• Using Attributes (C# Programming Guide)

• Creating Custom Attributes (C# Programming Guide)

• Disambiguating Attribute Targets (C# Programming Guide)

• Accessing Attributes With Reflection (C# Programming Guide)

• How to: Create a C/C++ Union Using Attributes (C# Programming Guide)

• Common Attributes (C# Programming Guide)

• Attributes Sample

C# Language Specification

For more information, see the following sections in the C# Language Specification:

• 10.2.1 Attributes

• 17 Attributes

See Also

Concepts

C# Programming Guide

Attributes Overview

Common Uses for Attributes

Reference

Reflection (C# Programming Guide)

Change History

Date	History	Reason
July 2008	Updated overview section.	Content bug fix.