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TypeBuilder.MakeGenericType Method

Note: This method is new in the .NET Framework version 2.0.

Substitutes the elements of an array of types for the type parameters of the current generic type definition, and returns the resulting constructed type.

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

public override Type MakeGenericType (
	params Type[] typeArguments
public Type MakeGenericType (
	Type[] typeArguments
public override function MakeGenericType (
	... typeArguments : Type[]
) : Type



An array of types to be substituted for the type parameters of the current generic type definition.

Return Value

A Type representing the constructed type formed by substituting the elements of typeArguments for the type parameters of the current generic type.

Exception typeCondition


The current type does not represent the definition of a generic type. That is, IsGenericTypeDefinition returns false.


typeArguments is a null reference (Nothing in Visual Basic).


Any element of typeArguments is a null reference (Nothing in Visual Basic).


The number of elements in typeArguments is not the same as the number of type parameters in the current generic type definition.


Any element of typeArguments does not satisfy the constraints specified for the corresponding type parameter of the current generic type.

Use this method when your emitted code requires a type constructed from the current generic type definition. It is not necessary to call the CreateType method before calling the MakeGenericType method on a TypeBuilder that represents a generic type definition. If the current TypeBuilder does not represent the definition of a generic type, an InvalidOperationException is thrown.

The object returned by this method functions as a placeholder for a constructed generic type in your emitted code. It is an instance of a class derived from Type that has limited capabilities. In particular:

  • To get methods, fields, and constructors for these constructed generic types, use the GetMethod(Type,MethodInfo), GetField(Type,FieldInfo), and GetConstructor(Type,ConstructorInfo) method overloads.

  • Two instances that represent the same constructed type do not compare as equal. For example, in the following code t1.Equals(t2) returns false:

    Dim t1 As Type = tbldr.MakeGenericType(GetType(String))
    Dim t2 As Type = tbldr.MakeGenericType(GetType(String))
    Dim result As Boolean = t1.Equals(t2)

    Type t1 = tbldr.MakeGenericType(typeof(string));
    Type t2 = tbldr.MakeGenericType(typeof(string));
    bool result = t1.Equals(t2);

    Type^ t1 = tbldr->MakeGenericType(String::typeid);
    Type^ t2 = tbldr->MakeGenericType(String::typeid);
    bool result = t1->Equals(t2);

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

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

.NET Framework

Supported in: 2.0