CLSCompliantAttribute Class
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CLSCompliantAttribute Class


Indicates whether a program element is compliant with the Common Language Specification (CLS). This class cannot be inherited.

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


[AttributeUsageAttribute(AttributeTargets.All, Inherited = true, 
	AllowMultiple = false)]
public sealed class CLSCompliantAttribute : Attribute


Initializes an instance of the CLSCompliantAttribute class with a Boolean value indicating whether the indicated program element is CLS-compliant.


Gets the Boolean value indicating whether the indicated program element is CLS-compliant.


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)


Returns the hash code for this instance.(Inherited from Attribute.)


Gets the Type of the current instance.(Inherited from Object.)


When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

The CLSCompliantAttribute attribute is used to indicate whether a particular program element complies with the Common Language Specification (CLS), which defines the features that any language that targets the .NET Framework must support. CLS compliance is primarily of concern to library developers who want to ensure that their libraries are accessible in any language that targets the .NET Framework. For more information, See Language Independence and Language-Independent Components.

You can apply the CLSCompliantAttribute attribute to the following program elements: assembly, module, class, struct, enum, constructor, method, property, field, event, interface, delegate, parameter, and return value. However, the notion of CLS compliance is only meaningful for assemblies, modules, types, and members of types, not parts of a member signature. Consequently, CLSCompliantAttribute is ignored when applied to parameter or return value program elements.

If no CLSCompliantAttribute is applied to a program element, then by default:

  • The assembly is not CLS-compliant.

  • The type is CLS-compliant only if its enclosing type or assembly is CLS-compliant.

  • The member of a type is CLS-compliant only if the type is CLS-compliant.

If an assembly is marked as CLS-compliant, any publicly exposed type in the assembly that is not CLS-compliant must be marked with CLSCompliantAttribute using a false argument. Similarly, if a class is marked as CLS-compliant, you must individually mark all members that are not CLS-compliant. All non-compliant members must provide corresponding CLS-compliant alternatives.

Attributes that are applied to assemblies or modules must occur after the C# using (Imports in Visual Basic) clauses and before the code.

For more information about using attributes, see Extending Metadata Using Attributes.


The current Microsoft Visual Basic compiler intentionally does not generate a CLS-compliance warning, however, a future release of the compiler will issue that warning.

The following example applies a CLSCompliantAttribute to the entire assembly.

using System;
    [assembly: CLSCompliant(true)]

The following declaration generates a CLS-compliance warning because the type UInt32 is not specified in the CLS.

public int SetValue(UInt32 value);

If the declaration is marked with a CLSCompliantAttribute, no compiler warning or error is generated.

 public int SetValue(UInt32 value);

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

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

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