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11/18/2011

ParameterBuilder Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Creates or associates parameter information.

Inheritance Hierarchy

System.Object
System.Reflection.Emit.ParameterBuilder

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

Syntax

'Declaration
<ClassInterfaceAttribute(ClassInterfaceType.None)> _
<ComVisibleAttribute(True)> _
Public Class ParameterBuilder

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

The ParameterBuilder type exposes the following members.

Properties

	Name	Description
	Attributes	Gets the attributes for this parameter.
	IsIn	Gets a value that indicates whether this is an input parameter.
	IsOptional	Gets a value that indicates whether this parameter is optional.
	IsOut	Gets a value that indicates whether this parameter is an output parameter.
	Name	Gets the name of this parameter.
	Position	Gets the signature position for this parameter.

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Methods

	Name	Description
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetToken	Gets the token for this parameter.
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	SetConstant	Sets the default value of the parameter.
	SetCustomAttribute(CustomAttributeBuilder)	Set a custom attribute using a custom attribute builder.
	SetCustomAttribute(ConstructorInfo, array<Byte[])	Security Critical. Set a custom attribute using a specified custom attribute blob.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

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").

Examples

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

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.


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

 _

Class Example

   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 Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      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()

      outputBlock.Text &= "---" & vbCrLf

      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
      outputBlock.Text &= String.Format("The pool is currently ${0}", thePool) & vbCrLf
      outputBlock.Text &= String.Format("The original balance of the account instance is ${0}", initialBalance) & vbCrLf

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

      outputBlock.Text &= "---" & vbCrLf
      outputBlock.Text &= String.Format("Calling {0} ...", myMemberInfo(0).ToString()) & vbCrLf
      outputBlock.Text &= "---" & vbCrLf

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

   End Sub 'Main 

End Class 'ParamBuilderDemo


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

class Example
{

   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 Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      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();

      outputBlock.Text += "---" + "\n";

      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;
      outputBlock.Text += String.Format("The pool is currently ${0}", thePool) + "\n";
      outputBlock.Text += String.Format("The original balance of the account instance is ${0}",
                        initialBalance) + "\n";

      double amountFromPool = 50.00;
      outputBlock.Text += String.Format("The amount to be subtracted from the pool and added " +
              "to the account is ${0}", amountFromPool) + "\n";

      outputBlock.Text += "---" + "\n";
      outputBlock.Text += String.Format("Calling {0} ...", myMemberInfo[0].ToString()) + "\n";
      outputBlock.Text += "---" + "\n";

      object[] passMe = new object[] { thePool, amountFromPool };
      outputBlock.Text += String.Format("The new balance in the account instance is ${0}",
                  custType.InvokeMember("AddFundsFromPool",
                  BindingFlags.InvokeMethod,
                  null, custObj, passMe)) + "\n";
      thePool = (double)passMe[0];
      outputBlock.Text += String.Format("The new amount in the pool is ${0}", thePool) + "\n";

   }

}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

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

Thread Safety

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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