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InternalsVisibleToAttribute Class

Updated: May 2011

Specifies that types that are ordinarily visible only within the current assembly are visible to a specified assembly.

System.Object
  System.Attribute
    System.Runtime.CompilerServices.InternalsVisibleToAttribute

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

[<Sealed>]
[<AttributeUsageAttribute(AttributeTargets.Assembly, AllowMultiple = true, Inherited = false)>]
type InternalsVisibleToAttribute =  
    class
        inherit Attribute
    end

The InternalsVisibleToAttribute type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryInternalsVisibleToAttributeInitializes a new instance of the InternalsVisibleToAttribute class with the name of the specified friend assembly.
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  NameDescription
Public propertyAllInternalsVisibleInfrastructure. This property is not implemented.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryAssemblyNameGets the name of the friend assembly to which all types and type members that are marked with the internal keyword are to be made visible.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodSupported by the XNA FrameworkMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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Ordinarily, types and members with internal scope (in C#) and friend scope (in Visual Basic) are visible only in the assembly in which they are defined. The InternalsVisibleToAttribute attribute makes them also visible to the types in a specified assembly, which is known as a friend assembly.

The attribute is applied at the assembly level. This means that it can be included at the beginning of a source code file, or it can be included in the AssemblyInfo file in a Visual Studio project. You can use the attribute to specify a single friend assembly that can access the internal types and members of the current assembly. You can define multiple friend assemblies in two ways. They can appear as individual assembly-level attributes, as the following example illustrates.

No code example is currently available or this language may not be supported.

They can also appear with separate InternalsVisibleToAttribute tags but a single assembly keyword, as the following example illustrates.

No code example is currently available or this language may not be supported.

The friend assembly is identified by the InternalsVisibleToAttribute constructor. Both the current assembly and the friend assembly must be unsigned, or both must be signed with a strong name. If they are signed with a strong name, the argument to the InternalsVisibleToAttribute constructor must include the full public key as well as the name of the assembly. For more information about using InternalsVisibleToAttribute with strong-named assemblies, see the InternalsVisibleToAttribute constructor.

Do not include values for the CultureInfo, Version, or ProcessorArchitecture fields in the argument to the constructor; the Visual Basic, C#, and C++ compilers treat this as a compiler error. If you use a compiler that does not treat it as an error (such as the Ilasm.exe (MSIL Assembler)) and the assemblies are strong-named, a MethodAccessException is thrown the first time the specified friend assembly accesses the assembly that contains the InternalsVisibleToAttribute attribute.

If you use the C# compiler to compile the friend assembly, you must explicitly specify the name of the output file (.exe or .dll) by using the /out compiler option. This is required because the compiler has not yet generated the name for the assembly it is building at the time it is binding to external references. The /out compiler option is optional for the Visual Basic compiler, and the corresponding --out or –o compiler option should not be used when compiling friend assemblies with the F# compiler.

For more information about how to use this attribute, see the following topics:

The following example defines a FileUtilities class that includes an internal AppendDirectorySeparator method. The InternalsVisibleToAttribute attribute is applied to the assembly that contains the FileUtilities class. The attribute allows an assembly named Friend1 to access this internal member.

No code example is currently available or this language may not be supported.

If the following example is compiled into a strong-named assembly named Friend1, the Example.Main method in Friend1 can successfully call the FileUtilities.AppendDirectorySeparator method, even though the method is internal to the Assembly1 assembly.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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

Date

History

Reason

May 2011

Added a discussion of compiler differences and of how to specify multiple friend assemblies.

Content bug fix.

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