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ParameterBuilder Class

Creates or associates parameter information.

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

'Declaration
<ClassInterfaceAttribute(ClassInterfaceType.None)> _
<ComVisibleAttribute(True)> _
Public Class ParameterBuilder _
	Implements _ParameterBuilder
'Usage
Dim instance As ParameterBuilder

Parameter attributes need to consistent with the method signature. If you specify Out attributes for a parameter, you should ensure that the type of that method parameter is a ByRef type.

Some ParameterBuilder attributes require that you call DefineMethod with viable parameters in order for the Microsoft intermediate language (MSIL) to work correctly at runtime. For example, if you define a ParameterBuilder with ParameterAttributes.Out for parameter 1 of a MethodBuilder, then parameter 1 of MethodBuilder must be a reference such as Type.GetType("System.String&"), rather than Type.GetType("System.String").

The following example demonstrates how to create a dynamic method with a parameter passed by reference using ParameterBuilder.

Imports System
Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit

 _

Class ParamBuilderDemo

   Public Shared Function BuildCustomerDataType() As Type

      Dim myDomain As AppDomain = Thread.GetDomain()
      Dim myAsmName As New AssemblyName()
      myAsmName.Name = "MyDynamicAssembly" 

      Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, _
						AssemblyBuilderAccess.Run)

      Dim myModBuilder As ModuleBuilder = myAsmBuilder.DefineDynamicModule("MyMod")

      Dim myTypeBuilder As TypeBuilder = myModBuilder.DefineType("CustomerData", TypeAttributes.Public)

      Dim customerNameBldr As FieldBuilder = myTypeBuilder.DefineField("customerName", _
								GetType(String), _
								FieldAttributes.Private)
      Dim acctIDBldr As FieldBuilder = myTypeBuilder.DefineField("acctID", _
								GetType(String), _
								FieldAttributes.Private)
      Dim balanceAmtBldr As FieldBuilder = myTypeBuilder.DefineField("balanceAmt", _
								GetType(Double), _
								FieldAttributes.Private)

      Dim myCtorBuilder As ConstructorBuilder = myTypeBuilder.DefineConstructor(MethodAttributes.Public, _
								CallingConventions.HasThis, _
								New Type() {GetType(String), _
									    GetType(String), _
									    GetType(Double)})


      Dim ctorIL As ILGenerator = myCtorBuilder.GetILGenerator()

      Dim objType As Type = Type.GetType("System.Object")
      Dim objCtor As ConstructorInfo = objType.GetConstructor(New Type(){})

      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Call, objCtor)

      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_1)
      ctorIL.Emit(OpCodes.Stfld, customerNameBldr)

      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_2)
      ctorIL.Emit(OpCodes.Stfld, acctIDBldr)

      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_3)
      ctorIL.Emit(OpCodes.Stfld, balanceAmtBldr)

      ctorIL.Emit(OpCodes.Ret)

      ' This method will take an amount from a static pool and add it to the balance. 
      ' Note that we are passing the first parameter, fundsPool, by reference. Therefore, 
      ' we need to inform the MethodBuilder to expect a ref, by declaring the first 
      ' parameter's type to be System.Double& (a reference to a double). 

      Dim myMthdBuilder As MethodBuilder = myTypeBuilder.DefineMethod("AddFundsFromPool", _
								MethodAttributes.Public, _
								GetType(Double), _
								New Type() {Type.GetType("System.Double&"), _
										 GetType(Double)})

      Dim poolRefBuilder As ParameterBuilder = myMthdBuilder.DefineParameter(1, _
							ParameterAttributes.Out, "fundsPool")

      Dim amountFromPoolBuilder As ParameterBuilder = myMthdBuilder.DefineParameter(2, _
							ParameterAttributes.In, "amountFromPool")

      Dim mthdIL As ILGenerator = myMthdBuilder.GetILGenerator()

      mthdIL.Emit(OpCodes.Ldarg_1)
      mthdIL.Emit(OpCodes.Ldarg_1)
      mthdIL.Emit(OpCodes.Ldind_R8)
      mthdIL.Emit(OpCodes.Ldarg_2)
      mthdIL.Emit(OpCodes.Sub)

      mthdIL.Emit(OpCodes.Stind_R8)

      mthdIL.Emit(OpCodes.Ldarg_0)
      mthdIL.Emit(OpCodes.Ldarg_0)
      mthdIL.Emit(OpCodes.Ldfld, balanceAmtBldr)
      mthdIL.Emit(OpCodes.Ldarg_2)
      mthdIL.Emit(OpCodes.Add)

      mthdIL.Emit(OpCodes.Stfld, balanceAmtBldr)

      mthdIL.Emit(OpCodes.Ldarg_0)
      mthdIL.Emit(OpCodes.Ldfld, balanceAmtBldr)
      mthdIL.Emit(OpCodes.Ret)

      Return myTypeBuilder.CreateType()

   End Function 'BuildCustomerDataType


   Public Shared Sub Main()

      Dim custType As Type = Nothing 
      Dim custObj As Object = Nothing 

      Dim custArgTypes() As Type = {GetType(String), GetType(String), GetType(Double)}

      ' Call the method to build our dynamic class.
      custType = BuildCustomerDataType()

      Console.WriteLine("---")

      Dim myCustCtor As ConstructorInfo = custType.GetConstructor(custArgTypes)
      Dim initialBalance As Double = 100.0
      custObj = myCustCtor.Invoke(New Object() {"Joe Consumer", "5678-XYZ", initialBalance})

      Dim myMemberInfo As MemberInfo() = custType.GetMember("AddFundsFromPool")


      Dim thePool As Double = 1000.0
      Console.WriteLine("The pool is currently ${0}", thePool)
      Console.WriteLine("The original balance of the account instance is ${0}", initialBalance)

      Dim amountFromPool As Double = 50.0
      Console.WriteLine("The amount to be subtracted from the pool and added " & _
			"to the account is ${0}", amountFromPool)

      Console.WriteLine("---")
      Console.WriteLine("Calling {0} ...", myMemberInfo(0).ToString())
      Console.WriteLine("---")

      Dim passMe() As Object = {thePool, amountFromPool}
      Console.WriteLine("The new balance in the account instance is ${0}", _
				custType.InvokeMember("AddFundsFromPool", _
				BindingFlags.InvokeMethod, Nothing, custObj, passMe))
      thePool = CDbl(passMe(0))
      Console.WriteLine("The new amount in the pool is ${0}", thePool)

   End Sub 'Main 

End Class 'ParamBuilderDemo

System.Object
  System.Reflection.Emit.ParameterBuilder

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

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, 1.1, 1.0
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