C# in a Nutshell, Second Edition

Name

AttributeTargets

Synopsis

This enumeration is used to set the AttributeUsageAttribute.ValidOn property when creating a custom attribute. It allows you to specify the code elements for which a custom attribute can be used. You can use a bitwise combination of these values to specify multiple elements.

Using this attribute is the only means by which a custom attribute can declare a restriction of its usage against various metadata types. For example, when using the System.Reflection.AssemblyKeyFileAttribute attribute, which simply tells the compiler which public/private keyfile to use to sign the assembly, it makes no sense to apply to any other metadata type besides the assembly. Therefore, the AssemblyKeyFileAttribute attribute has an AttributeUsageAttribute (see the AttributeUsageAttribute entry) declared on it with the value Assembly. As a result, any attempt to use the AssemblyKeyFileAttribute attribute on anything other than an assembly results in a compilation error.

public enum AttributeTargets {
   Assembly = 0x00000001,
   Module = 0x00000002,
   Class = 0x00000004,
   Struct = 0x00000008,
   Enum = 0x00000010,
   Constructor = 0x00000020,
   Method = 0x00000040,
   Property = 0x00000080,
   Field = 0x00000100,
   Event = 0x00000200,
   Interface = 0x00000400,
   Parameter = 0x00000800,
   Delegate = 0x00001000,
   ReturnValue = 0x00002000,
   All = 0x00003FFF
}

Hierarchy

Object → ValueType → Enum(IComparable, IFormattable, IConvertible) → AttributeTargets

Returned By

AttributeUsageAttribute.ValidOn

Passed To

AttributeUsageAttribute.AttributeUsageAttribute( ...