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GenericParameterAttributes Enumeration

Describes the constraints on a generic type parameter of a generic type or method.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

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

[<FlagsAttribute>]
type GenericParameterAttributes

Member nameDescription
Supported by Portable Class LibraryNoneThere are no special flags.
Supported by Portable Class LibraryVarianceMaskSelects the combination of all variance flags. This value is the result of using logical OR to combine the following flags: Contravariant and Covariant.
Supported by Portable Class LibraryCovariantThe generic type parameter is covariant. A covariant type parameter can appear as the result type of a method, the type of a read-only field, a declared base type, or an implemented interface.
Supported by Portable Class LibraryContravariantThe generic type parameter is contravariant. A contravariant type parameter can appear as a parameter type in method signatures.
Supported by Portable Class LibrarySpecialConstraintMaskSelects the combination of all special constraint flags. This value is the result of using logical OR to combine the following flags: DefaultConstructorConstraint, ReferenceTypeConstraint, and NotNullableValueTypeConstraint.
Supported by Portable Class LibraryReferenceTypeConstraintA type can be substituted for the generic type parameter only if it is a reference type.
Supported by Portable Class LibraryNotNullableValueTypeConstraintA type can be substituted for the generic type parameter only if it is a value type and is not nullable.
Supported by Portable Class LibraryDefaultConstructorConstraintA type can be substituted for the generic type parameter only if it has a parameterless constructor.

The members of the GenericParameterAttributes enumeration are divided into two groups, the variance group and the special constraints group. To test a GenericParameterAttributes value for variance flags, first perform a bitwise AND operation with VarianceMask. If the result is None, there are no variance flags. Similarly, use SpecialConstraintMask to test for constraint flags.

The following code example defines a generic type Test with two type parameters. The second type parameter has a base class constraint and a reference type constraint. When the program executes, the constraints are examined using the Type.GenericParameterAttributes property and the Type.GetGenericParameterConstraints method.

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.

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