Indicates to compilers that a method call or attribute should be ignored unless a specified conditional compilation symbol is defined.
Assembly: mscorlib (in mscorlib.dll)
Thetype exposes the following members.
|Equals||Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)|
|GetHashCode||Returns the hash code for this instance. (Inherited from Attribute.)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|IsDefaultAttribute||When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)|
|Match||When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
|_Attribute::GetIDsOfNames||Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)|
|_Attribute::GetTypeInfo||Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)|
|_Attribute::GetTypeInfoCount||Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)|
|_Attribute::Invoke||Provides access to properties and methods exposed by an object. (Inherited from Attribute.)|
You can apply the attribute to methods and classes. However, its use on classes is valid only for types that are derived from Attribute. either will be ignored or will produce a compiler warning or error message if you apply it to any other type.
Applying to a method indicates to compilers that a call to the method should not be compiled into Microsoft intermediate language (MSIL) unless the conditional compilation symbol that is associated with is defined. You will get a compilation error in Visual Studio if you apply this attribute to a method that does not return void. Applying to an attribute indicates that the attribute should not be emitted to metadata unless the conditional compilation symbol is defined. Any arguments passed to the method or attribute are still type-checked by the compiler.
You can use the following techniques to define conditional compilation symbols:
Use compiler command-line options; for example, /define:DEBUG.
Use environment variables in the operating system shell; for example, set DEBUG=1.
Use pragmas in the source code; for example, define the compilation variable as follows:
To undefine the variable, use the following:
Compilers that comply with the Common Language Specification (CLS) are permitted to ignore . The C#, Visual Basic, and C++ compilers support ; the JScript compiler does not support the attribute.
In Visual Basic, the AddressOf operator is not affected by this attribute. For example, Call CType(AddressOf delegate, Action) always invokes delegate, although Call delegate() might not.
For more information about how to use attributes, see Extending Metadata Using Attributes.
The following example demonstrates the use of . The example assumes that the condition is defined with the /define compiler option. You can obtain different results by changing the compiler option. You can optionally define the conditions by using pragmas in the sample code instead of identifying them as compiler options.
.NET FrameworkSupported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
Portable Class LibrarySupported in: Portable Class Library
.NET for Windows Store appsSupported in: Windows 8
.NET for Windows Phone appsSupported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.