ParameterBuilder Class
Assembly: mscorlib (in mscorlib.dll)
'Declaration <ClassInterfaceAttribute(ClassInterfaceType.None)> _ <ComVisibleAttribute(True)> _ Public Class ParameterBuilder Implements _ParameterBuilder 'Usage Dim instance As ParameterBuilder
/** @attribute ClassInterfaceAttribute(ClassInterfaceType.None) */ /** @attribute ComVisibleAttribute(true) */ public class ParameterBuilder implements _ParameterBuilder
ClassInterfaceAttribute(ClassInterfaceType.None) ComVisibleAttribute(true) public class ParameterBuilder implements _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
import System.*;
import System.Threading.*;
import System.Reflection.*;
import System.Reflection.Emit.*;
class ParamBuilderDemo
{
public static Type BuildCustomerDataType()
{
AppDomain myDomain = System.Threading.Thread.GetDomain();
AssemblyName myAsmName = new AssemblyName();
myAsmName.set_Name("MyDynamicAssembly");
AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly
(myAsmName, AssemblyBuilderAccess.Run);
ModuleBuilder myModBuilder = myAsmBuilder.DefineDynamicModule("MyMod");
TypeBuilder myTypeBuilder = myModBuilder.DefineType("CustomerData",
TypeAttributes.Public);
FieldBuilder customerNameBldr = myTypeBuilder.DefineField
("customerName", String.class.ToType(), FieldAttributes.Private);
FieldBuilder acctIDBldr = myTypeBuilder.DefineField("acctID",
String.class.ToType(), FieldAttributes.Private);
FieldBuilder balanceAmtBldr = myTypeBuilder.DefineField("balanceAmt",
double.class.ToType(), FieldAttributes.Private);
ConstructorBuilder myCtorBuilder = myTypeBuilder.DefineConstructor
(MethodAttributes.Public, CallingConventions.HasThis,
new Type[]{String.class.ToType(), String.class.ToType(),
double.class.ToType()});
ILGenerator ctorIL = myCtorBuilder.GetILGenerator();
Type objType = Type.GetType("System.Object");
ConstructorInfo objCtor = 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).
MethodBuilder myMthdBuilder = myTypeBuilder.DefineMethod
("AddFundsFromPool", MethodAttributes.Public,
double.class.ToType(),
new Type[]{Type.GetType("System.Double&"),
double.class.ToType()});
ParameterBuilder poolRefBuilder = myMthdBuilder.DefineParameter(1,
ParameterAttributes.Out, "fundsPool");
ParameterBuilder amountFromPoolBuilder =
myMthdBuilder.DefineParameter(2, ParameterAttributes.In,
"amountFromPool");
ILGenerator mthdIL = 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() ;
} //BuildCustomerDataType
public static void main(String[] args)
{
Type custType = null;
Object custObj = null;
Type custArgTypes[] = new Type[]{String.class.ToType(),
String.class.ToType(), double.class.ToType()};
// Call the method to build our dynamic class.
custType = BuildCustomerDataType();
Console.WriteLine("---");
ConstructorInfo myCustCtor = custType.GetConstructor(custArgTypes);
double initialBalance = 100.0;
custObj = myCustCtor.Invoke(new Object[]{"Joe Consumer", "5678-XYZ",
(System.Double)(initialBalance)});
MemberInfo myMemberInfo[] = custType.GetMember("AddFundsFromPool");
double thePool = 1000.0;
Console.WriteLine("The pool is currently ${0}",
System.Convert.ToString(thePool));
Console.WriteLine(
"The original balance of the account instance is ${0}",
new Object[] { (System.Double)(initialBalance) });
double amountFromPool = 50.0;
Console.WriteLine("The amount to be subtracted from the pool and added"
+ " to the account is ${0}", (System.Double)(amountFromPool));
Console.WriteLine("---");
Console.WriteLine("Calling {0} ...",
myMemberInfo .get_Item( 0).ToString());
Console.WriteLine("---");
Object passMe[] = new Object[] { (System.Double)(thePool),
(System.Double)(amountFromPool) };
Console.WriteLine("The new balance in the account instance is ${0}",
custType.InvokeMember("AddFundsFromPool",
BindingFlags.InvokeMethod, null, custObj, passMe));
thePool = (double)Double.parseDouble(passMe[0].toString());
Console.WriteLine("The new amount in the pool is ${0}",
(System.Double)(thePool));
} //main
} //ParamBuilderDemo
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.