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GenericTypeParameterBuilder Class

Defines and creates generic type parameters for dynamically defined generic types and methods. This class cannot be inherited.

System.Object
  System.Reflection.MemberInfo
    System.Type
      System.Reflection.Emit.GenericTypeParameterBuilder

Namespace:  System.Reflection.Emit
Assembly:  mscorlib (in mscorlib.dll)
[ComVisibleAttribute(true)]
public sealed class GenericTypeParameterBuilder : Type

The GenericTypeParameterBuilder type exposes the following members.

  NameDescription
Public propertyAssemblyGets an Assembly object representing the dynamic assembly that contains the generic type definition the current type parameter belongs to. (Overrides Type.Assembly.)
Public propertyAssemblyQualifiedNameGets null in all cases. (Overrides Type.AssemblyQualifiedName.)
Public propertyAttributesGets the attributes associated with the Type. (Inherited from Type.)
Public propertyBaseTypeGets the base type constraint of the current generic type parameter. (Overrides Type.BaseType.)
Public propertyContainsGenericParametersGets true in all cases. (Overrides Type.ContainsGenericParameters.)
Public propertyDeclaringMethodGets a MethodInfo that represents the declaring method, if the current GenericTypeParameterBuilder represents a type parameter of a generic method. (Overrides Type.DeclaringMethod.)
Public propertyDeclaringTypeGets the generic type definition or generic method definition to which the generic type parameter belongs. (Overrides Type.DeclaringType.)
Public propertyFullNameGets null in all cases. (Overrides Type.FullName.)
Public propertyGenericParameterAttributesGets a combination of GenericParameterAttributes flags that describe the covariance and special constraints of the current generic type parameter. (Inherited from Type.)
Public propertyGenericParameterPositionGets the position of the type parameter in the type parameter list of the generic type or method that declared the parameter. (Overrides Type.GenericParameterPosition.)
Public propertyGUIDNot supported for incomplete generic type parameters. (Overrides Type.GUID.)
Public propertyHasElementTypeGets a value indicating whether the current Type encompasses or refers to another type; that is, whether the current Type is an array, a pointer, or is passed by reference. (Inherited from Type.)
Public propertyIsAbstractGets a value indicating whether the Type is abstract and must be overridden. (Inherited from Type.)
Public propertyIsAnsiClassGets a value indicating whether the string format attribute AnsiClass is selected for the Type. (Inherited from Type.)
Public propertyIsArrayGets a value indicating whether the Type is an array. (Inherited from Type.)
Public propertyIsAutoClassGets a value indicating whether the string format attribute AutoClass is selected for the Type. (Inherited from Type.)
Public propertyIsAutoLayoutGets a value indicating whether the class layout attribute AutoLayout is selected for the Type. (Inherited from Type.)
Public propertyIsByRefGets a value indicating whether the Type is passed by reference. (Inherited from Type.)
Public propertyIsClassGets a value indicating whether the Type is a class; that is, not a value type or interface. (Inherited from Type.)
Public propertyIsCOMObjectGets a value indicating whether the Type is a COM object. (Inherited from Type.)
Public propertyIsEnumGets a value indicating whether the current Type represents an enumeration. (Inherited from Type.)
Public propertyIsGenericParameterGets true in all cases. (Overrides Type.IsGenericParameter.)
Public propertyIsGenericTypeReturns false in all cases. (Overrides Type.IsGenericType.)
Public propertyIsGenericTypeDefinitionGets false in all cases. (Overrides Type.IsGenericTypeDefinition.)
Public propertyIsImportGets a value indicating whether the Type has a ComImportAttribute attribute applied, indicating that it was imported from a COM type library. (Inherited from Type.)
Public propertyIsInterfaceGets a value indicating whether the Type is an interface; that is, not a class or a value type. (Inherited from Type.)
Public propertyIsNestedGets a value indicating whether the current Type object represents a type whose definition is nested inside the definition of another type. (Inherited from Type.)
Public propertyIsNestedAssemblyGets a value indicating whether the Type is nested and visible only within its own assembly. (Inherited from Type.)
Public propertyIsNestedFamANDAssemGets a value indicating whether the Type is nested and visible only to classes that belong to both its own family and its own assembly. (Inherited from Type.)
Public propertyIsNestedFamilyGets a value indicating whether the Type is nested and visible only within its own family. (Inherited from Type.)
Public propertyIsNestedFamORAssemGets a value indicating whether the Type is nested and visible only to classes that belong to either its own family or to its own assembly. (Inherited from Type.)
Public propertyIsNestedPrivateGets a value indicating whether the Type is nested and declared private. (Inherited from Type.)
Public propertyIsNestedPublicGets a value indicating whether a class is nested and declared public. (Inherited from Type.)
Public propertyIsNotPublicGets a value indicating whether the Type is not declared public. (Inherited from Type.)
Public propertyIsPointerGets a value indicating whether the Type is a pointer. (Inherited from Type.)
Public propertyIsPrimitiveGets a value indicating whether the Type is one of the primitive types. (Inherited from Type.)
Public propertyIsPublicGets a value indicating whether the Type is declared public. (Inherited from Type.)
Public propertyIsSealedGets a value indicating whether the Type is declared sealed. (Inherited from Type.)
Public propertyIsSpecialNameGets a value indicating whether the Type has a name that requires special handling. (Inherited from Type.)
Public propertyIsUnicodeClassGets a value indicating whether the string format attribute UnicodeClass is selected for the Type. (Inherited from Type.)
Public propertyIsValueTypeGets a value indicating whether the Type is a value type. (Inherited from Type.)
Public propertyIsVisibleGets a value indicating whether the Type can be accessed by code outside the assembly. (Inherited from Type.)
Public propertyMemberTypeGets a MemberTypes value indicating that this member is a type or a nested type. (Inherited from Type.)
Public propertyMetadataTokenGets a value that identifies a metadata element. (Inherited from MemberInfo.)
Public propertyModuleGets the dynamic module that contains the generic type parameter. (Overrides Type.Module.)
Public propertyNameGets the name of the generic type parameter. (Overrides MemberInfo.Name.)
Public propertyNamespaceGets null in all cases. (Overrides Type.Namespace.)
Public propertyReflectedTypeGets the Type object that was used to obtain the GenericTypeParameterBuilder. (Overrides Type.ReflectedType.)
Public propertyTypeHandleNot supported for incomplete generic type parameters. (Overrides Type.TypeHandle.)
Public propertyUnderlyingSystemTypeGets the current generic type parameter. (Overrides Type.UnderlyingSystemType.)
Top
  NameDescription
Public methodEquals(Object)Tests whether the given object is an instance of EventToken and is equal to the current instance. (Overrides Type.Equals(Object).)
Public methodEquals(Type)Determines if the underlying system type of the current Type is the same as the underlying system type of the specified Type. (Inherited from Type.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodFindMembersReturns a filtered array of MemberInfo objects of the specified member type. (Inherited from Type.)
Public methodGetArrayRankGets the number of dimensions in an Array. (Inherited from Type.)
Protected methodGetAttributeFlagsImplWhen overridden in a derived class, implements the Attributes property and gets a bitmask indicating the attributes associated with the Type. (Inherited from Type.)
Public methodGetConstructor(Type[])Searches for a public instance constructor whose parameters match the types in the specified array. (Inherited from Type.)
Public methodGetConstructor(BindingFlags, Binder, Type[], ParameterModifier[])Searches for a constructor whose parameters match the specified argument types and modifiers, using the specified binding constraints. (Inherited from Type.)
Protected methodGetConstructorImplWhen overridden in a derived class, searches for a constructor whose parameters match the specified argument types and modifiers, using the specified binding constraints and the specified calling convention. (Inherited from Type.)
Public methodGetConstructors()Returns all the public constructors defined for the current Type. (Inherited from Type.)
Public methodGetConstructors(BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetConstructors(BindingFlags).)
Public methodGetCustomAttributes(Boolean)Not supported for incomplete generic type parameters. (Overrides MemberInfo.GetCustomAttributes(Boolean).)
Public methodGetCustomAttributes(Type, Boolean)Not supported for incomplete generic type parameters. (Overrides MemberInfo.GetCustomAttributes(Type, Boolean).)
Public methodGetDefaultMembersSearches for the members defined for the current Type whose DefaultMemberAttribute is set. (Inherited from Type.)
Public methodGetElementTypeThrows a NotSupportedException in all cases. (Overrides Type.GetElementType().)
Public methodGetEvent(String)Returns the EventInfo object representing the specified public event. (Inherited from Type.)
Public methodGetEvent(String, BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetEvent(String, BindingFlags).)
Public methodGetEvents()Not supported for incomplete generic type parameters. (Overrides Type.GetEvents().)
Public methodGetEvents(BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetEvents(BindingFlags).)
Public methodGetField(String)Searches for the public field with the specified name. (Inherited from Type.)
Public methodGetField(String, BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetField(String, BindingFlags).)
Public methodGetFields()Returns all the public fields of the current Type. (Inherited from Type.)
Public methodGetFields(BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetFields(BindingFlags).)
Public methodGetGenericArgumentsNot valid for generic type parameters. (Overrides Type.GetGenericArguments().)
Public methodGetGenericParameterConstraintsReturns an array of Type objects that represent the constraints on the current generic type parameter. (Inherited from Type.)
Public methodGetGenericTypeDefinitionNot valid for generic type parameters. (Overrides Type.GetGenericTypeDefinition().)
Public methodGetHashCodeReturns a 32-bit integer hash code for the current instance. (Overrides Type.GetHashCode().)
Public methodGetInterfaceNot supported for incomplete generic type parameters. (Overrides Type.GetInterface(String, Boolean).)
Public methodGetInterfaceMapNot supported for incomplete generic type parameters. (Overrides Type.GetInterfaceMap(Type).)
Public methodGetInterfacesNot supported for incomplete generic type parameters. (Overrides Type.GetInterfaces().)
Public methodGetMember(String)Searches for the public members with the specified name. (Inherited from Type.)
Public methodGetMember(String, BindingFlags)Searches for the specified members, using the specified binding constraints. (Inherited from Type.)
Public methodGetMember(String, MemberTypes, BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetMember(String, MemberTypes, BindingFlags).)
Public methodGetMembers()Returns all the public members of the current Type. (Inherited from Type.)
Public methodGetMembers(BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetMembers(BindingFlags).)
Public methodGetMethod(String)Searches for the public method with the specified name. (Inherited from Type.)
Public methodGetMethod(String, BindingFlags)Searches for the specified method, using the specified binding constraints. (Inherited from Type.)
Public methodGetMethod(String, Type[])Searches for the specified public method whose parameters match the specified argument types. (Inherited from Type.)
Public methodGetMethod(String, Type[], ParameterModifier[])Searches for the specified public method whose parameters match the specified argument types and modifiers. (Inherited from Type.)
Public methodGetMethod(String, BindingFlags, Binder, Type[], ParameterModifier[])Searches for the specified method whose parameters match the specified argument types and modifiers, using the specified binding constraints. (Inherited from Type.)
Public methodGetMethod(String, BindingFlags, Binder, CallingConventions, Type[], ParameterModifier[])Searches for the specified method whose parameters match the specified argument types and modifiers, using the specified binding constraints and the specified calling convention. (Inherited from Type.)
Protected methodGetMethodImplWhen overridden in a derived class, searches for the specified method whose parameters match the specified argument types and modifiers, using the specified binding constraints and the specified calling convention. (Inherited from Type.)
Public methodGetMethods()Returns all the public methods of the current Type. (Inherited from Type.)
Public methodGetMethods(BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetMethods(BindingFlags).)
Public methodGetNestedTypeNot supported for incomplete generic type parameters. (Overrides Type.GetNestedType(String, BindingFlags).)
Public methodGetNestedTypesNot supported for incomplete generic type parameters. (Overrides Type.GetNestedTypes(BindingFlags).)
Public methodGetProperties()Returns all the public properties of the current Type. (Inherited from Type.)
Public methodGetProperties(BindingFlags)Not supported for incomplete generic type parameters. (Overrides Type.GetProperties(BindingFlags).)
Public methodGetProperty(String)Searches for the public property with the specified name. (Inherited from Type.)
Public methodGetProperty(String, BindingFlags)Searches for the specified property, using the specified binding constraints. (Inherited from Type.)
Public methodGetProperty(String, Type)Searches for the public property with the specified name and return type. (Inherited from Type.)
Public methodGetProperty(String, Type, Type[])Searches for the specified public property whose parameters match the specified argument types. (Inherited from Type.)
Public methodGetProperty(String, Type, Type[], ParameterModifier[])Searches for the specified public property whose parameters match the specified argument types and modifiers. (Inherited from Type.)
Public methodGetProperty(String, BindingFlags, Binder, Type, Type[], ParameterModifier[])Searches for the specified property whose parameters match the specified argument types and modifiers, using the specified binding constraints. (Inherited from Type.)
Protected methodGetPropertyImplWhen overridden in a derived class, searches for the specified property whose parameters match the specified argument types and modifiers, using the specified binding constraints. (Inherited from Type.)
Public methodGetType()Gets the current Type. (Inherited from Type.)
Protected methodHasElementTypeImplWhen overridden in a derived class, implements the HasElementType property and determines whether the current Type encompasses or refers to another type; that is, whether the current Type is an array, a pointer, or is passed by reference. (Inherited from Type.)
Public methodInvokeMember(String, BindingFlags, Binder, Object, Object[])Invokes the specified member, using the specified binding constraints and matching the specified argument list. (Inherited from Type.)
Public methodInvokeMember(String, BindingFlags, Binder, Object, Object[], ParameterModifier[], CultureInfo, String[])Not supported for incomplete generic type parameters. (Overrides Type.InvokeMember(String, BindingFlags, Binder, Object, Object[], ParameterModifier[], CultureInfo, String[]).)
Protected methodIsArrayImplWhen overridden in a derived class, implements the IsArray property and determines whether the Type is an array. (Inherited from Type.)
Public methodIsAssignableFromNot supported for incomplete generic type parameters. (Overrides Type.IsAssignableFrom(Type).)
Protected methodIsByRefImplWhen overridden in a derived class, implements the IsByRef property and determines whether the Type is passed by reference. (Inherited from Type.)
Protected methodIsCOMObjectImplWhen overridden in a derived class, implements the IsCOMObject property and determines whether the Type is a COM object. (Inherited from Type.)
Public methodIsDefinedNot supported for incomplete generic type parameters. (Overrides MemberInfo.IsDefined(Type, Boolean).)
Public methodIsInstanceOfTypeDetermines whether the specified object is an instance of the current Type. (Inherited from Type.)
Protected methodIsPointerImplWhen overridden in a derived class, implements the IsPointer property and determines whether the Type is a pointer. (Inherited from Type.)
Protected methodIsPrimitiveImplWhen overridden in a derived class, implements the IsPrimitive property and determines whether the Type is one of the primitive types. (Inherited from Type.)
Public methodIsSubclassOfNot supported for incomplete generic type parameters. (Overrides Type.IsSubclassOf(Type).)
Protected methodIsValueTypeImplImplements the IsValueType property and determines whether the Type is a value type; that is, not a class or an interface. (Inherited from Type.)
Public methodMakeArrayType()Returns the type of a one-dimensional array whose element type is the generic type parameter. (Overrides Type.MakeArrayType().)
Public methodMakeArrayType(Int32)Returns the type of an array whose element type is the generic type parameter, with the specified number of dimensions. (Overrides Type.MakeArrayType(Int32).)
Public methodMakeByRefTypeReturns a Type object that represents the current generic type parameter when passed as a reference parameter. (Overrides Type.MakeByRefType().)
Public methodMakeGenericTypeNot valid for incomplete generic type parameters. (Overrides Type.MakeGenericType(Type[]).)
Public methodMakePointerTypeReturns a Type object that represents a pointer to the current generic type parameter. (Overrides Type.MakePointerType().)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSetBaseTypeConstraintSets the base type that a type must inherit in order to be substituted for the type parameter.
Public methodSetCustomAttributeSet a custom attribute using a custom attribute builder.
Public methodSetGenericParameterAttributesSets the variance characteristics and special constraints of the generic parameter, such as the parameterless constructor constraint.
Public methodSetInterfaceConstraintsSets the interfaces a type must implement in order to be substituted for the type parameter.
Public methodToStringReturns a string representation of the current generic type parameter. (Overrides Type.ToString().)
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You can get an array of GenericTypeParameterBuilder objects by using the TypeBuilder.DefineGenericParameters method to add type parameters to a dynamic type, thus making it a generic type, or by using the MethodBuilder.DefineGenericParameters method to add type parameters to a dynamic method. Use the GenericTypeParameterBuilder objects to add constraints to the type parameters. Constraints are of three kinds:

  • The base type constraint specifies that any type assigned to the generic type parameter must derive from a particular base type. Set this constraint by using the SetBaseTypeConstraint method.

  • An interface constraint specifies that any type assigned to the generic type parameter must implement a particular interface. Set the interface constraints by using the SetInterfaceConstraints method.

  • Special constraints specify that any type assigned to the generic type parameter must have a default constructor, must be a reference type, or must be a value type. Set the special constraints for a type parameter by using the SetGenericParameterAttributes method.

Interface constraints and special constraints cannot be retrieved using methods of the GenericTypeParameterBuilder class. Once you have created the generic type that contains the type parameters, you can use its Type object to reflect the constraints. Use the Type.GetGenericArguments method to get the type parameters, and for each type parameter use the Type.GetGenericParameterConstraints method to get the base type constraint and interface constraints, and the Type.GenericParameterAttributes property to get the special constraints.

The following code example creates a generic type with two type parameters. For a more detailed explanation of the steps involved in defining a dynamic generic type, see How to: Define a Generic Type with Reflection Emit.


using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Collections.Generic;

// Define a trivial base class and two trivial interfaces 
// to use when demonstrating constraints.
//
public class ExampleBase { }

public interface IExampleA { }

public interface IExampleB { }

// Define a trivial type that can substitute for type parameter 
// TSecond.
//
public class ExampleDerived : ExampleBase, IExampleA, IExampleB { }


public class Example
{
   // Make the output TextBlock available to all methods.
   private static System.Windows.Controls.TextBlock outputBlock;

   public static void Demo(System.Windows.Controls.TextBlock output)
   {
      outputBlock = output;

      // Define a dynamic assembly to contain the sample type. In Silverlight,
      // a dynamic assembly contains one module.
      //
      AppDomain myDomain = AppDomain.CurrentDomain;
      AssemblyName myAsmName = new AssemblyName("GenericEmitExample1");
      AssemblyBuilder myAssembly =
          myDomain.DefineDynamicAssembly(myAsmName,
              AssemblyBuilderAccess.Run);
      ModuleBuilder myModule =
          myAssembly.DefineDynamicModule(myAsmName.Name);

      // Get type objects for the base class trivial interfaces to
      // be used as constraints.
      //
      Type baseType = typeof(ExampleBase);
      Type interfaceA = typeof(IExampleA);
      Type interfaceB = typeof(IExampleB);

      // Define the sample type.
      //
      TypeBuilder myType =
          myModule.DefineType("Sample", TypeAttributes.Public);

      outputBlock.Text += String.Format("Type 'Sample' is generic: {0}",
          myType.IsGenericType) + "\n";

      // Define type parameters for the type. Until you do this, 
      // the type is not generic, as the preceding and following 
      // WriteLine statements show. The type parameter names are
      // specified as an array of strings. To make the code
      // easier to read, each GenericTypeParameterBuilder is placed
      // in a variable with the same name as the type parameter.
      // 
      string[] typeParamNames = { "TFirst", "TSecond" };
      GenericTypeParameterBuilder[] typeParams =
          myType.DefineGenericParameters(typeParamNames);

      GenericTypeParameterBuilder TFirst = typeParams[0];
      GenericTypeParameterBuilder TSecond = typeParams[1];

      outputBlock.Text += String.Format("Type 'Sample' is generic: {0}",
          myType.IsGenericType) + "\n";

      // Apply constraints to the type parameters.
      //
      // A type that is substituted for the first parameter, TFirst,
      // must be a reference type and must have a parameterless
      // constructor.
      TFirst.SetGenericParameterAttributes(
          GenericParameterAttributes.DefaultConstructorConstraint |
          GenericParameterAttributes.ReferenceTypeConstraint);

      // A type that is substituted for the second type
      // parameter must implement IExampleA and IExampleB, and
      // inherit from the trivial test class ExampleBase. The
      // interface constraints are specified as an array 
      // containing the interface types.
      TSecond.SetBaseTypeConstraint(baseType);
      Type[] interfaceTypes = { interfaceA, interfaceB };
      TSecond.SetInterfaceConstraints(interfaceTypes);

      // The following code adds a private field named ExampleField,
      // of type TFirst.
      FieldBuilder exField =
          myType.DefineField("ExampleField", TFirst,
              FieldAttributes.Private);

      // Define a static method that takes an array of TFirst and 
      // returns a List<TFirst> containing all the elements of 
      // the array. To define this method it is necessary to create
      // the type List<TFirst> by calling MakeGenericType on the
      // generic type definition, List<T>. (The T is omitted with
      // the typeof operator when you get the generic type 
      // definition.) The parameter type is created by using the
      // MakeArrayType method. 
      //
      Type listOf = typeof(List<>);
      Type listOfTFirst = listOf.MakeGenericType(TFirst);
      Type[] mParamTypes = { TFirst.MakeArrayType() };

      MethodBuilder exMethod =
          myType.DefineMethod("ExampleMethod",
              MethodAttributes.Public | MethodAttributes.Static,
              listOfTFirst,
              mParamTypes);

      // Emit the method body. 
      // The method body consists of just three opcodes, to load 
      // the input array onto the execution stack, to call the 
      // List<TFirst> constructor that takes IEnumerable<TFirst>,
      // which does all the work of putting the input elements into
      // the list, and to return, leaving the list on the stack. The
      // hard work is getting the constructor.
      // 
      // The GetConstructor method is not supported on a 
      // GenericTypeParameterBuilder, so it is not possible to get 
      // the constructor of List<TFirst> directly. There are two
      // steps, first getting the constructor of List<T> and then
      // calling a method that converts it to the corresponding 
      // constructor of List<TFirst>.
      //
      // The constructor needed here is the one that takes an
      // IEnumerable<T>. Note, however, that this is not the 
      // generic type definition of IEnumerable<T>; instead, the
      // T from List<T> must be substituted for the T of 
      // IEnumerable<T>. (This seems confusing only because both
      // types have type parameters named T. That is why this example
      // uses the somewhat silly names TFirst and TSecond.) To get
      // the type of the constructor argument, take the generic
      // type definition IEnumerable<T> (expressed as 
      // IEnumerable<> when you use the typeof operator) and 
      // call MakeGenericType with the first generic type parameter
      // of List<T>. The constructor argument list must be passed
      // as an array, with just one argument in this case.
      // 
      // Now it is possible to get the constructor of List<T>,
      // using GetConstructor on the generic type definition. To get
      // the constructor of List<TFirst>, pass List<TFirst> and
      // the constructor from List<T> to the static
      // TypeBuilder.GetConstructor method.
      //
      ILGenerator ilgen = exMethod.GetILGenerator();

      Type ienumOf = typeof(IEnumerable<>);
      Type TfromListOf = listOf.GetGenericArguments()[0];
      Type ienumOfT = ienumOf.MakeGenericType(TfromListOf);
      Type[] ctorArgs = { ienumOfT };

      ConstructorInfo ctorPrep = listOf.GetConstructor(ctorArgs);
      ConstructorInfo ctor =
          TypeBuilder.GetConstructor(listOfTFirst, ctorPrep);

      ilgen.Emit(OpCodes.Ldarg_0);
      ilgen.Emit(OpCodes.Newobj, ctor);
      ilgen.Emit(OpCodes.Ret);

      // Create the type. 
      Type finished = myType.CreateType();

      // Invoke the method.
      // ExampleMethod is not generic, but the type it belongs to is
      // generic, so in order to get a MethodInfo that can be invoked
      // it is necessary to create a constructed type. The Example 
      // class satisfies the constraints on TFirst, because it is a 
      // reference type and has a default constructor. In order to
      // have a class that satisfies the constraints on TSecond, 
      // this code example defines the ExampleDerived type. These
      // two types are passed to MakeGenericMethod to create the
      // constructed type.
      //
      Type[] typeArgs = { typeof(Example), typeof(ExampleDerived) };
      Type constructed = finished.MakeGenericType(typeArgs);
      MethodInfo mi = constructed.GetMethod("ExampleMethod");

      // Create an array of Example objects, as input to the generic
      // method. This array must be passed as the only element of an 
      // array of arguments. The first argument of Invoke is 
      // null, because ExampleMethod is static. Display the count
      // on the resulting List<Example>.
      // 
      Example[] input = { new Example(), new Example() };
      object[] arguments = { input };

      List<Example> listX =
          (List<Example>)mi.Invoke(null, arguments);

      outputBlock.Text += String.Format(
          "\nThere are {0} elements in the List<Example>.",
          listX.Count) + "\n";

      DisplayGenericParameters(finished);
   }

   private static void DisplayGenericParameters(Type t)
   {
      if (!t.IsGenericType)
      {
         outputBlock.Text += String.Format("Type '{0}' is not generic.") + "\n";
         return;
      }
      if (!t.IsGenericTypeDefinition)
      {
         t = t.GetGenericTypeDefinition();
      }

      Type[] typeParameters = t.GetGenericArguments();
      outputBlock.Text += String.Format("\nListing {0} type parameters for type '{1}'.",
          typeParameters.Length, t) + "\n";

      foreach (Type tParam in typeParameters)
      {
         outputBlock.Text += String.Format("\r\nType parameter {0}:", tParam.ToString()) + "\n";

         foreach (Type c in tParam.GetGenericParameterConstraints())
         {
            if (c.IsInterface)
            {
               outputBlock.Text += String.Format("    Interface constraint: {0}", c) + "\n";
            }
            else
            {
               outputBlock.Text += String.Format("    Base type constraint: {0}", c) + "\n";
            }
         }

         ListConstraintAttributes(tParam);
      }
   }

   // List the constraint flags. The GenericParameterAttributes
   // enumeration contains two sets of attributes, variance and
   // constraints. For this example, only constraints are used.
   //
   private static void ListConstraintAttributes(Type t)
   {
      // Mask off the constraint flags. 
      GenericParameterAttributes constraints =
          t.GenericParameterAttributes & GenericParameterAttributes.SpecialConstraintMask;

      if ((constraints & GenericParameterAttributes.ReferenceTypeConstraint)
          != GenericParameterAttributes.None)
      {
         outputBlock.Text += "    ReferenceTypeConstraint" + "\n";
      }

      if ((constraints & GenericParameterAttributes.NotNullableValueTypeConstraint)
          != GenericParameterAttributes.None)
      {
         outputBlock.Text += "    NotNullableValueTypeConstraint" + "\n";
      }

      if ((constraints & GenericParameterAttributes.DefaultConstructorConstraint)
          != GenericParameterAttributes.None)
      {
         outputBlock.Text += "    DefaultConstructorConstraint" + "\n";
      }
   }
}

/* This code example produces the following output:

Type 'Sample' is generic: False
Type 'Sample' is generic: True

There are 2 elements in the List<Example>.

Listing 2 type parameters for type 'Sample[TFirst,TSecond]'.

Type parameter TFirst:
    ReferenceTypeConstraint
    DefaultConstructorConstraint

Type parameter TSecond:
    Interface constraint: IExampleA
    Interface constraint: IExampleB
    Base type constraint: ExampleBase
 */


Silverlight

Supported in: 5, 4, 3

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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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