ConditionalAttribute Class

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Indicates to compilers that a method call or attribute should be ignored unless a specified conditional compilation symbol is defined.

Inheritance Hierarchy


Namespace: System.Diagnostics
Assembly: mscorlib (in mscorlib.dll)


<AttributeUsageAttribute(AttributeTargets.Class Or AttributeTargets.Method, AllowMultiple := True)> _
Public NotInheritable Class ConditionalAttribute _
    Inherits Attribute
[AttributeUsageAttribute(AttributeTargets.Class|AttributeTargets.Method, AllowMultiple = true)]
public sealed class ConditionalAttribute : Attribute

The ConditionalAttribute type exposes the following members.


Name Description
ConditionalAttribute Initializes a new instance of the ConditionalAttribute class.



Name Description
ConditionString Gets the conditional compilation symbol that is associated with the ConditionalAttribute attribute.



Name Description
Equals Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Finalize Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
GetHashCode Returns the hash code for this instance. (Inherited from Attribute.)
GetType Gets the Type of the current instance. (Inherited from Object.)
Match When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
ToString Returns a string that represents the current object. (Inherited from Object.)



You can apply the ConditionalAttribute attribute to methods and classes. However, its use on classes is valid only for types that are derived from Attribute. ConditionalAttribute either will be ignored or will produce a compiler warning or error message if you apply it to any other type.

Applying ConditionalAttribute 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 ConditionalAttribute is defined. Applying ConditionalAttribute 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:

  • Compiler command-line options (for example, /define:DEBUG).

  • Environment variables in the operating system shell (for example, set DEBUG=1).

  • Pragmas in the source code (for example, #define DEBUG to define the compilation variable and #undef DEBUG to undefine it).

Compilers that comply with the Common Language Specification (CLS) are permitted to ignore ConditionalAttribute. The C#, J#, and Visual Basic compilers support ConditionalAttribute; the C++ and JScript compilers do not support the attribute.

ConditionalAttribute is applied to the methods that are defined in the Debug class.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0


Windows Phone

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also


System.Diagnostics Namespace