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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)

public enum GenericParameterAttributes

Member nameDescription
NoneThere are no special flags.
VarianceMaskSelects the combination of all variance flags. This value is the result of using logical OR to combine the following flags: Contravariant and Covariant.
CovariantThe 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.
ContravariantThe generic type parameter is contravariant. A contravariant type parameter can appear as a parameter type in method signatures.
SpecialConstraintMaskSelects 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.
ReferenceTypeConstraintA type can be substituted for the generic type parameter only if it is a reference type.
NotNullableValueTypeConstraintA type can be substituted for the generic type parameter only if it is a value type and is not nullable.
DefaultConstructorConstraintA 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.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0

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