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ParameterBuilder Class

Creates or associates parameter information.

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

[ClassInterfaceAttribute(ClassInterfaceType.None)] 
[ComVisibleAttribute(true)] 
public class ParameterBuilder : _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.


using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;

class ParamBuilderDemo 

{

   public static Type BuildCustomerDataType()
   {

	AppDomain myDomain = Thread.GetDomain();
	AssemblyName myAsmName = new AssemblyName();
	myAsmName.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",
							typeof(string),
							FieldAttributes.Private);
	FieldBuilder acctIDBldr = myTypeBuilder.DefineField("acctID",
						 	typeof(string),
							FieldAttributes.Private);
	FieldBuilder balanceAmtBldr = myTypeBuilder.DefineField("balanceAmt",
							typeof(double),
							FieldAttributes.Private);
								
	ConstructorBuilder myCtorBuilder = myTypeBuilder.DefineConstructor(
							MethodAttributes.Public,
							CallingConventions.HasThis, 
							new Type[] { typeof(string),
								     typeof(string),
								     typeof(double) });


	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,
						typeof(double),
						new Type[] { Type.GetType("System.Double&"),
							     typeof(double) });

	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();

   }

   public static void Main()
   {
 	Type custType = null;
	object custObj = null;

	Type[] custArgTypes = new Type[] {typeof(string), typeof(string), typeof(double)};
	
	// Call the method to build our dynamic class.

	custType = BuildCustomerDataType();

	Console.WriteLine("---");

	ConstructorInfo myCustCtor = custType.GetConstructor(custArgTypes);
	double initialBalance = 100.00;
	custObj = myCustCtor.Invoke(new object[] { "Joe Consumer", 
						   "5678-XYZ", 
					  	   initialBalance });

	MemberInfo[] myMemberInfo = custType.GetMember("AddFundsFromPool");


	double thePool = 1000.00;
	Console.WriteLine("The pool is currently ${0}", thePool);
	Console.WriteLine("The original balance of the account instance is ${0}",
							initialBalance);

	double amountFromPool = 50.00;
	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("---");

	object[] passMe = new object[] { thePool, amountFromPool };
	Console.WriteLine("The new balance in the account instance is ${0}",
					custType.InvokeMember("AddFundsFromPool",
					BindingFlags.InvokeMethod,
					null, custObj, passMe));
	thePool = (double)passMe[0];
	Console.WriteLine("The new amount in the pool is ${0}", thePool);

   }

}


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

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 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, 1.1, 1.0
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