ILGenerator.EmitWriteLine Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Helper functions to emit a call to WriteLine() with different types of values.
Overloads
| EmitWriteLine(String) |
Emits the Microsoft intermediate language (MSIL) to call WriteLine with a string. |
| EmitWriteLine(FieldInfo) |
Emits the Microsoft intermediate language (MSIL) necessary to call WriteLine with the given field. |
| EmitWriteLine(LocalBuilder) |
Emits the Microsoft intermediate language (MSIL) necessary to call WriteLine with the given local variable. |
EmitWriteLine(String)
- Source:
- ILGenerator.cs
- Source:
- ILGenerator.cs
- Source:
- ILGenerator.cs
Emits the Microsoft intermediate language (MSIL) to call WriteLine with a string.
public:
virtual void EmitWriteLine(System::String ^ value);public virtual void EmitWriteLine (string value);abstract member EmitWriteLine : string -> unit
override this.EmitWriteLine : string -> unitPublic Overridable Sub EmitWriteLine (value As String)Parameters
- value
- String
The string to be printed.
Examples
The code sample below demonstrates the contextual usage of the EmitWriteLine method to write a string to the console in a dynamic method.
using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ CreateDynamicType()
{
array<Type^>^ctorParams = {int::typeid,int::typeid};
AppDomain^ myDomain = Thread::GetDomain();
AssemblyName^ myAsmName = gcnew AssemblyName;
myAsmName->Name = "MyDynamicAssembly";
AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::Run );
ModuleBuilder^ pointModule = myAsmBuilder->DefineDynamicModule( "PointModule", "Point.dll" );
TypeBuilder^ pointTypeBld = pointModule->DefineType( "Point", TypeAttributes::Public );
FieldBuilder^ xField = pointTypeBld->DefineField( "x", int::typeid, FieldAttributes::Public );
FieldBuilder^ yField = pointTypeBld->DefineField( "y", int::typeid, FieldAttributes::Public );
Type^ objType = Type::GetType( "System.Object" );
ConstructorInfo^ objCtor = objType->GetConstructor( gcnew array<Type^>(0) );
ConstructorBuilder^ pointCtor = pointTypeBld->DefineConstructor( MethodAttributes::Public, CallingConventions::Standard, ctorParams );
ILGenerator^ ctorIL = pointCtor->GetILGenerator();
// First, you build the constructor.
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Call, objCtor );
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_1 );
ctorIL->Emit( OpCodes::Stfld, xField );
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_2 );
ctorIL->Emit( OpCodes::Stfld, yField );
ctorIL->Emit( OpCodes::Ret );
// Now, you'll build a method to output some information on the
// inside your dynamic class. This method will have the following
// definition in C#:
// public void WritePoint()
MethodBuilder^ writeStrMthd = pointTypeBld->DefineMethod( "WritePoint", MethodAttributes::Public, void::typeid, nullptr );
ILGenerator^ writeStrIL = writeStrMthd->GetILGenerator();
// The below ILGenerator created demonstrates a few ways to create
// String* output through STDIN.
// ILGenerator::EmitWriteLine(String*) will generate a ldstr and a
// call to WriteLine for you.
writeStrIL->EmitWriteLine( "The value of this current instance is:" );
// Here, you will do the hard work yourself. First, you need to create
// the String* we will be passing and obtain the correct WriteLine overload
// for said String*. In the below case, you are substituting in two values,
// so the chosen overload is Console::WriteLine(String*, Object*, Object*).
String^ inStr = "( {0}, {1})";
array<Type^>^wlParams = {String::typeid,Object::typeid,Object::typeid};
// We need the MethodInfo to pass into EmitCall later.
MethodInfo^ writeLineMI = Console::typeid->GetMethod( "WriteLine", wlParams );
// Push the String* with the substitutions onto the stack.
// This is the first argument for WriteLine - the String* one.
writeStrIL->Emit( OpCodes::Ldstr, inStr );
// Since the second argument is an Object*, and it corresponds to
// to the substitution for the value of our integer field, you
// need to box that field to an Object*. First, push a reference
// to the current instance, and then push the value stored in
// field 'x'. We need the reference to the current instance (stored
// in local argument index 0) so Ldfld can load from the correct
// instance (this one).
writeStrIL->Emit( OpCodes::Ldarg_0 );
writeStrIL->Emit( OpCodes::Ldfld, xField );
// Now, we execute the box opcode, which pops the value of field 'x',
// returning a reference to the integer value boxed as an Object*.
writeStrIL->Emit( OpCodes::Box, int::typeid );
// Atop the stack, you'll find our String* inStr, followed by a reference
// to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL->Emit( OpCodes::Ldarg_0 );
writeStrIL->Emit( OpCodes::Ldfld, yField );
writeStrIL->Emit( OpCodes::Box, int::typeid );
// Now, you have all of the arguments for your call to
// Console::WriteLine(String*, Object*, Object*) atop the stack:
// the String* InStr, a reference to the boxed value of 'x', and
// a reference to the boxed value of 'y'.
// Call Console::WriteLine(String*, Object*, Object*) with EmitCall.
writeStrIL->EmitCall( OpCodes::Call, writeLineMI, nullptr );
// Lastly, EmitWriteLine can also output the value of a field
// using the overload EmitWriteLine(FieldInfo).
writeStrIL->EmitWriteLine( "The value of 'x' is:" );
writeStrIL->EmitWriteLine( xField );
writeStrIL->EmitWriteLine( "The value of 'y' is:" );
writeStrIL->EmitWriteLine( yField );
// Since we return no value (void), the ret opcode will not
// return the top stack value.
writeStrIL->Emit( OpCodes::Ret );
return pointTypeBld->CreateType();
}
int main()
{
array<Object^>^ctorParams = gcnew array<Object^>(2);
Console::Write( "Enter a integer value for X: " );
String^ myX = Console::ReadLine();
Console::Write( "Enter a integer value for Y: " );
String^ myY = Console::ReadLine();
Console::WriteLine( "---" );
ctorParams[ 0 ] = Convert::ToInt32( myX );
ctorParams[ 1 ] = Convert::ToInt32( myY );
Type^ ptType = CreateDynamicType();
Object^ ptInstance = Activator::CreateInstance( ptType, ctorParams );
ptType->InvokeMember( "WritePoint", BindingFlags::InvokeMethod, nullptr, ptInstance, gcnew array<Object^>(0) );
}
using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
class EmitWriteLineDemo {
public static Type CreateDynamicType() {
Type[] ctorParams = new Type[] {typeof(int),
typeof(int)};
AppDomain myDomain = Thread.GetDomain();
AssemblyName myAsmName = new AssemblyName();
myAsmName.Name = "MyDynamicAssembly";
AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
myAsmName,
AssemblyBuilderAccess.Run);
ModuleBuilder pointModule = myAsmBuilder.DefineDynamicModule("PointModule",
"Point.dll");
TypeBuilder pointTypeBld = pointModule.DefineType("Point",
TypeAttributes.Public);
FieldBuilder xField = pointTypeBld.DefineField("x", typeof(int),
FieldAttributes.Public);
FieldBuilder yField = pointTypeBld.DefineField("y", typeof(int),
FieldAttributes.Public);
Type objType = Type.GetType("System.Object");
ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);
ConstructorBuilder pointCtor = pointTypeBld.DefineConstructor(
MethodAttributes.Public,
CallingConventions.Standard,
ctorParams);
ILGenerator ctorIL = pointCtor.GetILGenerator();
// First, you build the constructor.
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Call, objCtor);
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_1);
ctorIL.Emit(OpCodes.Stfld, xField);
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_2);
ctorIL.Emit(OpCodes.Stfld, yField);
ctorIL.Emit(OpCodes.Ret);
// Now, you'll build a method to output some information on the
// inside your dynamic class. This method will have the following
// definition in C#:
// public void WritePoint()
MethodBuilder writeStrMthd = pointTypeBld.DefineMethod(
"WritePoint",
MethodAttributes.Public,
typeof(void),
null);
ILGenerator writeStrIL = writeStrMthd.GetILGenerator();
// The below ILGenerator created demonstrates a few ways to create
// string output through STDIN.
// ILGenerator.EmitWriteLine(string) will generate a ldstr and a
// call to WriteLine for you.
writeStrIL.EmitWriteLine("The value of this current instance is:");
// Here, you will do the hard work yourself. First, you need to create
// the string we will be passing and obtain the correct WriteLine overload
// for said string. In the below case, you are substituting in two values,
// so the chosen overload is Console.WriteLine(string, object, object).
String inStr = "({0}, {1})";
Type[] wlParams = new Type[] {typeof(string),
typeof(object),
typeof(object)};
// We need the MethodInfo to pass into EmitCall later.
MethodInfo writeLineMI = typeof(Console).GetMethod(
"WriteLine",
wlParams);
// Push the string with the substitutions onto the stack.
// This is the first argument for WriteLine - the string one.
writeStrIL.Emit(OpCodes.Ldstr, inStr);
// Since the second argument is an object, and it corresponds to
// to the substitution for the value of our integer field, you
// need to box that field to an object. First, push a reference
// to the current instance, and then push the value stored in
// field 'x'. We need the reference to the current instance (stored
// in local argument index 0) so Ldfld can load from the correct
// instance (this one).
writeStrIL.Emit(OpCodes.Ldarg_0);
writeStrIL.Emit(OpCodes.Ldfld, xField);
// Now, we execute the box opcode, which pops the value of field 'x',
// returning a reference to the integer value boxed as an object.
writeStrIL.Emit(OpCodes.Box, typeof(int));
// Atop the stack, you'll find our string inStr, followed by a reference
// to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL.Emit(OpCodes.Ldarg_0);
writeStrIL.Emit(OpCodes.Ldfld, yField);
writeStrIL.Emit(OpCodes.Box, typeof(int));
// Now, you have all of the arguments for your call to
// Console.WriteLine(string, object, object) atop the stack:
// the string InStr, a reference to the boxed value of 'x', and
// a reference to the boxed value of 'y'.
// Call Console.WriteLine(string, object, object) with EmitCall.
writeStrIL.EmitCall(OpCodes.Call, writeLineMI, null);
// Lastly, EmitWriteLine can also output the value of a field
// using the overload EmitWriteLine(FieldInfo).
writeStrIL.EmitWriteLine("The value of 'x' is:");
writeStrIL.EmitWriteLine(xField);
writeStrIL.EmitWriteLine("The value of 'y' is:");
writeStrIL.EmitWriteLine(yField);
// Since we return no value (void), the ret opcode will not
// return the top stack value.
writeStrIL.Emit(OpCodes.Ret);
return pointTypeBld.CreateType();
}
public static void Main() {
object[] ctorParams = new object[2];
Console.Write("Enter a integer value for X: ");
string myX = Console.ReadLine();
Console.Write("Enter a integer value for Y: ");
string myY = Console.ReadLine();
Console.WriteLine("---");
ctorParams[0] = Convert.ToInt32(myX);
ctorParams[1] = Convert.ToInt32(myY);
Type ptType = CreateDynamicType();
object ptInstance = Activator.CreateInstance(ptType, ctorParams);
ptType.InvokeMember("WritePoint",
BindingFlags.InvokeMethod,
null,
ptInstance,
new object[0]);
}
}
Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit
_
Class EmitWriteLineDemo
Public Shared Function CreateDynamicType() As Type
Dim ctorParams() As Type = {GetType(Integer), GetType(Integer)}
Dim myDomain As AppDomain = Thread.GetDomain()
Dim myAsmName As New AssemblyName()
myAsmName.Name = "MyDynamicAssembly"
Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave)
Dim pointModule As ModuleBuilder = myAsmBuilder.DefineDynamicModule("PointModule", "Point.dll")
Dim pointTypeBld As TypeBuilder = pointModule.DefineType("Point", _
TypeAttributes.Public)
Dim xField As FieldBuilder = pointTypeBld.DefineField("x", _
GetType(Integer), _
FieldAttributes.Public)
Dim yField As FieldBuilder = pointTypeBld.DefineField("y", _
GetType(Integer), _
FieldAttributes.Public)
Dim objType As Type = Type.GetType("System.Object")
Dim objCtor As ConstructorInfo = objType.GetConstructor(New Type(){})
Dim pointCtor As ConstructorBuilder = pointTypeBld.DefineConstructor( _
MethodAttributes.Public, _
CallingConventions.Standard, _
ctorParams)
Dim ctorIL As ILGenerator = pointCtor.GetILGenerator()
' First, you build the constructor.
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Call, objCtor)
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_1)
ctorIL.Emit(OpCodes.Stfld, xField)
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_2)
ctorIL.Emit(OpCodes.Stfld, yField)
ctorIL.Emit(OpCodes.Ret)
' Now, you'll build a method to output some information on the
' inside your dynamic class. This method will have the following
' definition in C#:
' Public Sub WritePoint()
Dim writeStrMthd As MethodBuilder = pointTypeBld.DefineMethod("WritePoint", _
MethodAttributes.Public, _
Nothing, Nothing)
Dim writeStrIL As ILGenerator = writeStrMthd.GetILGenerator()
' The below ILGenerator created demonstrates a few ways to create
' string output through STDIN.
' ILGenerator.EmitWriteLine(string) will generate a ldstr and a
' call to WriteLine for you.
writeStrIL.EmitWriteLine("The value of this current instance is:")
' Here, you will do the hard work yourself. First, you need to create
' the string we will be passing and obtain the correct WriteLine overload
' for said string. In the below case, you are substituting in two values,
' so the chosen overload is Console.WriteLine(string, object, object).
Dim inStr As [String] = "({0}, {1})"
Dim wlParams() As Type = {GetType(String), GetType(Object), GetType(Object)}
' We need the MethodInfo to pass into EmitCall later.
Dim writeLineMI As MethodInfo = GetType(Console).GetMethod("WriteLine", wlParams)
' Push the string with the substitutions onto the stack.
' This is the first argument for WriteLine - the string one.
writeStrIL.Emit(OpCodes.Ldstr, inStr)
' Since the second argument is an object, and it corresponds to
' to the substitution for the value of our integer field, you
' need to box that field to an object. First, push a reference
' to the current instance, and then push the value stored in
' field 'x'. We need the reference to the current instance (stored
' in local argument index 0) so Ldfld can load from the correct
' instance (this one).
writeStrIL.Emit(OpCodes.Ldarg_0)
writeStrIL.Emit(OpCodes.Ldfld, xField)
' Now, we execute the box opcode, which pops the value of field 'x',
' returning a reference to the integer value boxed as an object.
writeStrIL.Emit(OpCodes.Box, GetType(Integer))
' Atop the stack, you'll find our string inStr, followed by a reference
' to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL.Emit(OpCodes.Ldarg_0)
writeStrIL.Emit(OpCodes.Ldfld, yField)
writeStrIL.Emit(OpCodes.Box, GetType(Integer))
' Now, you have all of the arguments for your call to
' Console.WriteLine(string, object, object) atop the stack:
' the string InStr, a reference to the boxed value of 'x', and
' a reference to the boxed value of 'y'.
' Call Console.WriteLine(string, object, object) with EmitCall.
writeStrIL.EmitCall(OpCodes.Call, writeLineMI, Nothing)
' Lastly, EmitWriteLine can also output the value of a field
' using the overload EmitWriteLine(FieldInfo).
writeStrIL.EmitWriteLine("The value of 'x' is:")
writeStrIL.EmitWriteLine(xField)
writeStrIL.EmitWriteLine("The value of 'y' is:")
writeStrIL.EmitWriteLine(yField)
' Since we return no value (void), the ret opcode will not
' return the top stack value.
writeStrIL.Emit(OpCodes.Ret)
Return pointTypeBld.CreateType()
End Function 'CreateDynamicType
Public Shared Sub Main()
Dim ctorParams(1) As Object
Console.Write("Enter a integer value for X: ")
Dim myX As String = Console.ReadLine()
Console.Write("Enter a integer value for Y: ")
Dim myY As String = Console.ReadLine()
Console.WriteLine("---")
ctorParams(0) = Convert.ToInt32(myX)
ctorParams(1) = Convert.ToInt32(myY)
Dim ptType As Type = CreateDynamicType()
Dim ptInstance As Object = Activator.CreateInstance(ptType, ctorParams)
ptType.InvokeMember("WritePoint", _
BindingFlags.InvokeMethod, _
Nothing, ptInstance, Nothing)
End Sub
End Class
Remarks
The string must have already been defined.
Applies to
EmitWriteLine(FieldInfo)
- Source:
- ILGenerator.cs
- Source:
- ILGenerator.cs
- Source:
- ILGenerator.cs
Emits the Microsoft intermediate language (MSIL) necessary to call WriteLine with the given field.
public:
virtual void EmitWriteLine(System::Reflection::FieldInfo ^ fld);public virtual void EmitWriteLine (System.Reflection.FieldInfo fld);abstract member EmitWriteLine : System.Reflection.FieldInfo -> unit
override this.EmitWriteLine : System.Reflection.FieldInfo -> unitPublic Overridable Sub EmitWriteLine (fld As FieldInfo)Parameters
- fld
- FieldInfo
The field whose value is to be written to the console.
Exceptions
There is no overload of the WriteLine method that accepts the type of the specified field.
fld is null.
The type of the field is TypeBuilder or EnumBuilder, which are not supported.
Examples
The following code sample demonstrates the use of the EmitWriteLine method to write a string to the console in a dynamic method.
using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ CreateDynamicType()
{
array<Type^>^ctorParams = {int::typeid,int::typeid};
AppDomain^ myDomain = Thread::GetDomain();
AssemblyName^ myAsmName = gcnew AssemblyName;
myAsmName->Name = "MyDynamicAssembly";
AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::Run );
ModuleBuilder^ pointModule = myAsmBuilder->DefineDynamicModule( "PointModule", "Point.dll" );
TypeBuilder^ pointTypeBld = pointModule->DefineType( "Point", TypeAttributes::Public );
FieldBuilder^ xField = pointTypeBld->DefineField( "x", int::typeid, FieldAttributes::Public );
FieldBuilder^ yField = pointTypeBld->DefineField( "y", int::typeid, FieldAttributes::Public );
Type^ objType = Type::GetType( "System.Object" );
ConstructorInfo^ objCtor = objType->GetConstructor( gcnew array<Type^>(0) );
ConstructorBuilder^ pointCtor = pointTypeBld->DefineConstructor( MethodAttributes::Public, CallingConventions::Standard, ctorParams );
ILGenerator^ ctorIL = pointCtor->GetILGenerator();
// First, you build the constructor.
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Call, objCtor );
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_1 );
ctorIL->Emit( OpCodes::Stfld, xField );
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_2 );
ctorIL->Emit( OpCodes::Stfld, yField );
ctorIL->Emit( OpCodes::Ret );
// Now, you'll build a method to output some information on the
// inside your dynamic class. This method will have the following
// definition in C#:
// public void WritePoint()
MethodBuilder^ writeStrMthd = pointTypeBld->DefineMethod( "WritePoint", MethodAttributes::Public, void::typeid, nullptr );
ILGenerator^ writeStrIL = writeStrMthd->GetILGenerator();
// The below ILGenerator created demonstrates a few ways to create
// String* output through STDIN.
// ILGenerator::EmitWriteLine(String*) will generate a ldstr and a
// call to WriteLine for you.
writeStrIL->EmitWriteLine( "The value of this current instance is:" );
// Here, you will do the hard work yourself. First, you need to create
// the String* we will be passing and obtain the correct WriteLine overload
// for said String*. In the below case, you are substituting in two values,
// so the chosen overload is Console::WriteLine(String*, Object*, Object*).
String^ inStr = "( {0}, {1})";
array<Type^>^wlParams = {String::typeid,Object::typeid,Object::typeid};
// We need the MethodInfo to pass into EmitCall later.
MethodInfo^ writeLineMI = Console::typeid->GetMethod( "WriteLine", wlParams );
// Push the String* with the substitutions onto the stack.
// This is the first argument for WriteLine - the String* one.
writeStrIL->Emit( OpCodes::Ldstr, inStr );
// Since the second argument is an Object*, and it corresponds to
// to the substitution for the value of our integer field, you
// need to box that field to an Object*. First, push a reference
// to the current instance, and then push the value stored in
// field 'x'. We need the reference to the current instance (stored
// in local argument index 0) so Ldfld can load from the correct
// instance (this one).
writeStrIL->Emit( OpCodes::Ldarg_0 );
writeStrIL->Emit( OpCodes::Ldfld, xField );
// Now, we execute the box opcode, which pops the value of field 'x',
// returning a reference to the integer value boxed as an Object*.
writeStrIL->Emit( OpCodes::Box, int::typeid );
// Atop the stack, you'll find our String* inStr, followed by a reference
// to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL->Emit( OpCodes::Ldarg_0 );
writeStrIL->Emit( OpCodes::Ldfld, yField );
writeStrIL->Emit( OpCodes::Box, int::typeid );
// Now, you have all of the arguments for your call to
// Console::WriteLine(String*, Object*, Object*) atop the stack:
// the String* InStr, a reference to the boxed value of 'x', and
// a reference to the boxed value of 'y'.
// Call Console::WriteLine(String*, Object*, Object*) with EmitCall.
writeStrIL->EmitCall( OpCodes::Call, writeLineMI, nullptr );
// Lastly, EmitWriteLine can also output the value of a field
// using the overload EmitWriteLine(FieldInfo).
writeStrIL->EmitWriteLine( "The value of 'x' is:" );
writeStrIL->EmitWriteLine( xField );
writeStrIL->EmitWriteLine( "The value of 'y' is:" );
writeStrIL->EmitWriteLine( yField );
// Since we return no value (void), the ret opcode will not
// return the top stack value.
writeStrIL->Emit( OpCodes::Ret );
return pointTypeBld->CreateType();
}
int main()
{
array<Object^>^ctorParams = gcnew array<Object^>(2);
Console::Write( "Enter a integer value for X: " );
String^ myX = Console::ReadLine();
Console::Write( "Enter a integer value for Y: " );
String^ myY = Console::ReadLine();
Console::WriteLine( "---" );
ctorParams[ 0 ] = Convert::ToInt32( myX );
ctorParams[ 1 ] = Convert::ToInt32( myY );
Type^ ptType = CreateDynamicType();
Object^ ptInstance = Activator::CreateInstance( ptType, ctorParams );
ptType->InvokeMember( "WritePoint", BindingFlags::InvokeMethod, nullptr, ptInstance, gcnew array<Object^>(0) );
}
using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
class EmitWriteLineDemo {
public static Type CreateDynamicType() {
Type[] ctorParams = new Type[] {typeof(int),
typeof(int)};
AppDomain myDomain = Thread.GetDomain();
AssemblyName myAsmName = new AssemblyName();
myAsmName.Name = "MyDynamicAssembly";
AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
myAsmName,
AssemblyBuilderAccess.Run);
ModuleBuilder pointModule = myAsmBuilder.DefineDynamicModule("PointModule",
"Point.dll");
TypeBuilder pointTypeBld = pointModule.DefineType("Point",
TypeAttributes.Public);
FieldBuilder xField = pointTypeBld.DefineField("x", typeof(int),
FieldAttributes.Public);
FieldBuilder yField = pointTypeBld.DefineField("y", typeof(int),
FieldAttributes.Public);
Type objType = Type.GetType("System.Object");
ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);
ConstructorBuilder pointCtor = pointTypeBld.DefineConstructor(
MethodAttributes.Public,
CallingConventions.Standard,
ctorParams);
ILGenerator ctorIL = pointCtor.GetILGenerator();
// First, you build the constructor.
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Call, objCtor);
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_1);
ctorIL.Emit(OpCodes.Stfld, xField);
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_2);
ctorIL.Emit(OpCodes.Stfld, yField);
ctorIL.Emit(OpCodes.Ret);
// Now, you'll build a method to output some information on the
// inside your dynamic class. This method will have the following
// definition in C#:
// public void WritePoint()
MethodBuilder writeStrMthd = pointTypeBld.DefineMethod(
"WritePoint",
MethodAttributes.Public,
typeof(void),
null);
ILGenerator writeStrIL = writeStrMthd.GetILGenerator();
// The below ILGenerator created demonstrates a few ways to create
// string output through STDIN.
// ILGenerator.EmitWriteLine(string) will generate a ldstr and a
// call to WriteLine for you.
writeStrIL.EmitWriteLine("The value of this current instance is:");
// Here, you will do the hard work yourself. First, you need to create
// the string we will be passing and obtain the correct WriteLine overload
// for said string. In the below case, you are substituting in two values,
// so the chosen overload is Console.WriteLine(string, object, object).
String inStr = "({0}, {1})";
Type[] wlParams = new Type[] {typeof(string),
typeof(object),
typeof(object)};
// We need the MethodInfo to pass into EmitCall later.
MethodInfo writeLineMI = typeof(Console).GetMethod(
"WriteLine",
wlParams);
// Push the string with the substitutions onto the stack.
// This is the first argument for WriteLine - the string one.
writeStrIL.Emit(OpCodes.Ldstr, inStr);
// Since the second argument is an object, and it corresponds to
// to the substitution for the value of our integer field, you
// need to box that field to an object. First, push a reference
// to the current instance, and then push the value stored in
// field 'x'. We need the reference to the current instance (stored
// in local argument index 0) so Ldfld can load from the correct
// instance (this one).
writeStrIL.Emit(OpCodes.Ldarg_0);
writeStrIL.Emit(OpCodes.Ldfld, xField);
// Now, we execute the box opcode, which pops the value of field 'x',
// returning a reference to the integer value boxed as an object.
writeStrIL.Emit(OpCodes.Box, typeof(int));
// Atop the stack, you'll find our string inStr, followed by a reference
// to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL.Emit(OpCodes.Ldarg_0);
writeStrIL.Emit(OpCodes.Ldfld, yField);
writeStrIL.Emit(OpCodes.Box, typeof(int));
// Now, you have all of the arguments for your call to
// Console.WriteLine(string, object, object) atop the stack:
// the string InStr, a reference to the boxed value of 'x', and
// a reference to the boxed value of 'y'.
// Call Console.WriteLine(string, object, object) with EmitCall.
writeStrIL.EmitCall(OpCodes.Call, writeLineMI, null);
// Lastly, EmitWriteLine can also output the value of a field
// using the overload EmitWriteLine(FieldInfo).
writeStrIL.EmitWriteLine("The value of 'x' is:");
writeStrIL.EmitWriteLine(xField);
writeStrIL.EmitWriteLine("The value of 'y' is:");
writeStrIL.EmitWriteLine(yField);
// Since we return no value (void), the ret opcode will not
// return the top stack value.
writeStrIL.Emit(OpCodes.Ret);
return pointTypeBld.CreateType();
}
public static void Main() {
object[] ctorParams = new object[2];
Console.Write("Enter a integer value for X: ");
string myX = Console.ReadLine();
Console.Write("Enter a integer value for Y: ");
string myY = Console.ReadLine();
Console.WriteLine("---");
ctorParams[0] = Convert.ToInt32(myX);
ctorParams[1] = Convert.ToInt32(myY);
Type ptType = CreateDynamicType();
object ptInstance = Activator.CreateInstance(ptType, ctorParams);
ptType.InvokeMember("WritePoint",
BindingFlags.InvokeMethod,
null,
ptInstance,
new object[0]);
}
}
Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit
_
Class EmitWriteLineDemo
Public Shared Function CreateDynamicType() As Type
Dim ctorParams() As Type = {GetType(Integer), GetType(Integer)}
Dim myDomain As AppDomain = Thread.GetDomain()
Dim myAsmName As New AssemblyName()
myAsmName.Name = "MyDynamicAssembly"
Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave)
Dim pointModule As ModuleBuilder = myAsmBuilder.DefineDynamicModule("PointModule", "Point.dll")
Dim pointTypeBld As TypeBuilder = pointModule.DefineType("Point", _
TypeAttributes.Public)
Dim xField As FieldBuilder = pointTypeBld.DefineField("x", _
GetType(Integer), _
FieldAttributes.Public)
Dim yField As FieldBuilder = pointTypeBld.DefineField("y", _
GetType(Integer), _
FieldAttributes.Public)
Dim objType As Type = Type.GetType("System.Object")
Dim objCtor As ConstructorInfo = objType.GetConstructor(New Type(){})
Dim pointCtor As ConstructorBuilder = pointTypeBld.DefineConstructor( _
MethodAttributes.Public, _
CallingConventions.Standard, _
ctorParams)
Dim ctorIL As ILGenerator = pointCtor.GetILGenerator()
' First, you build the constructor.
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Call, objCtor)
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_1)
ctorIL.Emit(OpCodes.Stfld, xField)
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_2)
ctorIL.Emit(OpCodes.Stfld, yField)
ctorIL.Emit(OpCodes.Ret)
' Now, you'll build a method to output some information on the
' inside your dynamic class. This method will have the following
' definition in C#:
' Public Sub WritePoint()
Dim writeStrMthd As MethodBuilder = pointTypeBld.DefineMethod("WritePoint", _
MethodAttributes.Public, _
Nothing, Nothing)
Dim writeStrIL As ILGenerator = writeStrMthd.GetILGenerator()
' The below ILGenerator created demonstrates a few ways to create
' string output through STDIN.
' ILGenerator.EmitWriteLine(string) will generate a ldstr and a
' call to WriteLine for you.
writeStrIL.EmitWriteLine("The value of this current instance is:")
' Here, you will do the hard work yourself. First, you need to create
' the string we will be passing and obtain the correct WriteLine overload
' for said string. In the below case, you are substituting in two values,
' so the chosen overload is Console.WriteLine(string, object, object).
Dim inStr As [String] = "({0}, {1})"
Dim wlParams() As Type = {GetType(String), GetType(Object), GetType(Object)}
' We need the MethodInfo to pass into EmitCall later.
Dim writeLineMI As MethodInfo = GetType(Console).GetMethod("WriteLine", wlParams)
' Push the string with the substitutions onto the stack.
' This is the first argument for WriteLine - the string one.
writeStrIL.Emit(OpCodes.Ldstr, inStr)
' Since the second argument is an object, and it corresponds to
' to the substitution for the value of our integer field, you
' need to box that field to an object. First, push a reference
' to the current instance, and then push the value stored in
' field 'x'. We need the reference to the current instance (stored
' in local argument index 0) so Ldfld can load from the correct
' instance (this one).
writeStrIL.Emit(OpCodes.Ldarg_0)
writeStrIL.Emit(OpCodes.Ldfld, xField)
' Now, we execute the box opcode, which pops the value of field 'x',
' returning a reference to the integer value boxed as an object.
writeStrIL.Emit(OpCodes.Box, GetType(Integer))
' Atop the stack, you'll find our string inStr, followed by a reference
' to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL.Emit(OpCodes.Ldarg_0)
writeStrIL.Emit(OpCodes.Ldfld, yField)
writeStrIL.Emit(OpCodes.Box, GetType(Integer))
' Now, you have all of the arguments for your call to
' Console.WriteLine(string, object, object) atop the stack:
' the string InStr, a reference to the boxed value of 'x', and
' a reference to the boxed value of 'y'.
' Call Console.WriteLine(string, object, object) with EmitCall.
writeStrIL.EmitCall(OpCodes.Call, writeLineMI, Nothing)
' Lastly, EmitWriteLine can also output the value of a field
' using the overload EmitWriteLine(FieldInfo).
writeStrIL.EmitWriteLine("The value of 'x' is:")
writeStrIL.EmitWriteLine(xField)
writeStrIL.EmitWriteLine("The value of 'y' is:")
writeStrIL.EmitWriteLine(yField)
' Since we return no value (void), the ret opcode will not
' return the top stack value.
writeStrIL.Emit(OpCodes.Ret)
Return pointTypeBld.CreateType()
End Function 'CreateDynamicType
Public Shared Sub Main()
Dim ctorParams(1) As Object
Console.Write("Enter a integer value for X: ")
Dim myX As String = Console.ReadLine()
Console.Write("Enter a integer value for Y: ")
Dim myY As String = Console.ReadLine()
Console.WriteLine("---")
ctorParams(0) = Convert.ToInt32(myX)
ctorParams(1) = Convert.ToInt32(myY)
Dim ptType As Type = CreateDynamicType()
Dim ptInstance As Object = Activator.CreateInstance(ptType, ctorParams)
ptType.InvokeMember("WritePoint", _
BindingFlags.InvokeMethod, _
Nothing, ptInstance, Nothing)
End Sub
End Class
Remarks
The type of fld must match the parameter type of an overload of the Console.WriteLine method.
Applies to
EmitWriteLine(LocalBuilder)
- Source:
- ILGenerator.cs
- Source:
- ILGenerator.cs
- Source:
- ILGenerator.cs
Emits the Microsoft intermediate language (MSIL) necessary to call WriteLine with the given local variable.
public:
virtual void EmitWriteLine(System::Reflection::Emit::LocalBuilder ^ localBuilder);public virtual void EmitWriteLine (System.Reflection.Emit.LocalBuilder localBuilder);abstract member EmitWriteLine : System.Reflection.Emit.LocalBuilder -> unit
override this.EmitWriteLine : System.Reflection.Emit.LocalBuilder -> unitPublic Overridable Sub EmitWriteLine (localBuilder As LocalBuilder)Parameters
- localBuilder
- LocalBuilder
The local variable whose value is to be written to the console.
Exceptions
The type of localBuilder is TypeBuilder or EnumBuilder, which are not supported.
-or-
There is no overload of WriteLine that accepts the type of localBuilder.
localBuilder is null.
Examples
The code sample below demonstrates the contextual usage of the EmitWriteLine method to write a string to the console in a dynamic method.
using namespace System;
using namespace System::Threading;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
Type^ CreateDynamicType()
{
array<Type^>^ctorParams = {int::typeid,int::typeid};
AppDomain^ myDomain = Thread::GetDomain();
AssemblyName^ myAsmName = gcnew AssemblyName;
myAsmName->Name = "MyDynamicAssembly";
AssemblyBuilder^ myAsmBuilder = myDomain->DefineDynamicAssembly( myAsmName, AssemblyBuilderAccess::Run );
ModuleBuilder^ pointModule = myAsmBuilder->DefineDynamicModule( "PointModule", "Point.dll" );
TypeBuilder^ pointTypeBld = pointModule->DefineType( "Point", TypeAttributes::Public );
FieldBuilder^ xField = pointTypeBld->DefineField( "x", int::typeid, FieldAttributes::Public );
FieldBuilder^ yField = pointTypeBld->DefineField( "y", int::typeid, FieldAttributes::Public );
Type^ objType = Type::GetType( "System.Object" );
ConstructorInfo^ objCtor = objType->GetConstructor( gcnew array<Type^>(0) );
ConstructorBuilder^ pointCtor = pointTypeBld->DefineConstructor( MethodAttributes::Public, CallingConventions::Standard, ctorParams );
ILGenerator^ ctorIL = pointCtor->GetILGenerator();
// First, you build the constructor.
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Call, objCtor );
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_1 );
ctorIL->Emit( OpCodes::Stfld, xField );
ctorIL->Emit( OpCodes::Ldarg_0 );
ctorIL->Emit( OpCodes::Ldarg_2 );
ctorIL->Emit( OpCodes::Stfld, yField );
ctorIL->Emit( OpCodes::Ret );
// Now, you'll build a method to output some information on the
// inside your dynamic class. This method will have the following
// definition in C#:
// public void WritePoint()
MethodBuilder^ writeStrMthd = pointTypeBld->DefineMethod( "WritePoint", MethodAttributes::Public, void::typeid, nullptr );
ILGenerator^ writeStrIL = writeStrMthd->GetILGenerator();
// The below ILGenerator created demonstrates a few ways to create
// String* output through STDIN.
// ILGenerator::EmitWriteLine(String*) will generate a ldstr and a
// call to WriteLine for you.
writeStrIL->EmitWriteLine( "The value of this current instance is:" );
// Here, you will do the hard work yourself. First, you need to create
// the String* we will be passing and obtain the correct WriteLine overload
// for said String*. In the below case, you are substituting in two values,
// so the chosen overload is Console::WriteLine(String*, Object*, Object*).
String^ inStr = "( {0}, {1})";
array<Type^>^wlParams = {String::typeid,Object::typeid,Object::typeid};
// We need the MethodInfo to pass into EmitCall later.
MethodInfo^ writeLineMI = Console::typeid->GetMethod( "WriteLine", wlParams );
// Push the String* with the substitutions onto the stack.
// This is the first argument for WriteLine - the String* one.
writeStrIL->Emit( OpCodes::Ldstr, inStr );
// Since the second argument is an Object*, and it corresponds to
// to the substitution for the value of our integer field, you
// need to box that field to an Object*. First, push a reference
// to the current instance, and then push the value stored in
// field 'x'. We need the reference to the current instance (stored
// in local argument index 0) so Ldfld can load from the correct
// instance (this one).
writeStrIL->Emit( OpCodes::Ldarg_0 );
writeStrIL->Emit( OpCodes::Ldfld, xField );
// Now, we execute the box opcode, which pops the value of field 'x',
// returning a reference to the integer value boxed as an Object*.
writeStrIL->Emit( OpCodes::Box, int::typeid );
// Atop the stack, you'll find our String* inStr, followed by a reference
// to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL->Emit( OpCodes::Ldarg_0 );
writeStrIL->Emit( OpCodes::Ldfld, yField );
writeStrIL->Emit( OpCodes::Box, int::typeid );
// Now, you have all of the arguments for your call to
// Console::WriteLine(String*, Object*, Object*) atop the stack:
// the String* InStr, a reference to the boxed value of 'x', and
// a reference to the boxed value of 'y'.
// Call Console::WriteLine(String*, Object*, Object*) with EmitCall.
writeStrIL->EmitCall( OpCodes::Call, writeLineMI, nullptr );
// Lastly, EmitWriteLine can also output the value of a field
// using the overload EmitWriteLine(FieldInfo).
writeStrIL->EmitWriteLine( "The value of 'x' is:" );
writeStrIL->EmitWriteLine( xField );
writeStrIL->EmitWriteLine( "The value of 'y' is:" );
writeStrIL->EmitWriteLine( yField );
// Since we return no value (void), the ret opcode will not
// return the top stack value.
writeStrIL->Emit( OpCodes::Ret );
return pointTypeBld->CreateType();
}
int main()
{
array<Object^>^ctorParams = gcnew array<Object^>(2);
Console::Write( "Enter a integer value for X: " );
String^ myX = Console::ReadLine();
Console::Write( "Enter a integer value for Y: " );
String^ myY = Console::ReadLine();
Console::WriteLine( "---" );
ctorParams[ 0 ] = Convert::ToInt32( myX );
ctorParams[ 1 ] = Convert::ToInt32( myY );
Type^ ptType = CreateDynamicType();
Object^ ptInstance = Activator::CreateInstance( ptType, ctorParams );
ptType->InvokeMember( "WritePoint", BindingFlags::InvokeMethod, nullptr, ptInstance, gcnew array<Object^>(0) );
}
using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
class EmitWriteLineDemo {
public static Type CreateDynamicType() {
Type[] ctorParams = new Type[] {typeof(int),
typeof(int)};
AppDomain myDomain = Thread.GetDomain();
AssemblyName myAsmName = new AssemblyName();
myAsmName.Name = "MyDynamicAssembly";
AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
myAsmName,
AssemblyBuilderAccess.Run);
ModuleBuilder pointModule = myAsmBuilder.DefineDynamicModule("PointModule",
"Point.dll");
TypeBuilder pointTypeBld = pointModule.DefineType("Point",
TypeAttributes.Public);
FieldBuilder xField = pointTypeBld.DefineField("x", typeof(int),
FieldAttributes.Public);
FieldBuilder yField = pointTypeBld.DefineField("y", typeof(int),
FieldAttributes.Public);
Type objType = Type.GetType("System.Object");
ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);
ConstructorBuilder pointCtor = pointTypeBld.DefineConstructor(
MethodAttributes.Public,
CallingConventions.Standard,
ctorParams);
ILGenerator ctorIL = pointCtor.GetILGenerator();
// First, you build the constructor.
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Call, objCtor);
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_1);
ctorIL.Emit(OpCodes.Stfld, xField);
ctorIL.Emit(OpCodes.Ldarg_0);
ctorIL.Emit(OpCodes.Ldarg_2);
ctorIL.Emit(OpCodes.Stfld, yField);
ctorIL.Emit(OpCodes.Ret);
// Now, you'll build a method to output some information on the
// inside your dynamic class. This method will have the following
// definition in C#:
// public void WritePoint()
MethodBuilder writeStrMthd = pointTypeBld.DefineMethod(
"WritePoint",
MethodAttributes.Public,
typeof(void),
null);
ILGenerator writeStrIL = writeStrMthd.GetILGenerator();
// The below ILGenerator created demonstrates a few ways to create
// string output through STDIN.
// ILGenerator.EmitWriteLine(string) will generate a ldstr and a
// call to WriteLine for you.
writeStrIL.EmitWriteLine("The value of this current instance is:");
// Here, you will do the hard work yourself. First, you need to create
// the string we will be passing and obtain the correct WriteLine overload
// for said string. In the below case, you are substituting in two values,
// so the chosen overload is Console.WriteLine(string, object, object).
String inStr = "({0}, {1})";
Type[] wlParams = new Type[] {typeof(string),
typeof(object),
typeof(object)};
// We need the MethodInfo to pass into EmitCall later.
MethodInfo writeLineMI = typeof(Console).GetMethod(
"WriteLine",
wlParams);
// Push the string with the substitutions onto the stack.
// This is the first argument for WriteLine - the string one.
writeStrIL.Emit(OpCodes.Ldstr, inStr);
// Since the second argument is an object, and it corresponds to
// to the substitution for the value of our integer field, you
// need to box that field to an object. First, push a reference
// to the current instance, and then push the value stored in
// field 'x'. We need the reference to the current instance (stored
// in local argument index 0) so Ldfld can load from the correct
// instance (this one).
writeStrIL.Emit(OpCodes.Ldarg_0);
writeStrIL.Emit(OpCodes.Ldfld, xField);
// Now, we execute the box opcode, which pops the value of field 'x',
// returning a reference to the integer value boxed as an object.
writeStrIL.Emit(OpCodes.Box, typeof(int));
// Atop the stack, you'll find our string inStr, followed by a reference
// to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL.Emit(OpCodes.Ldarg_0);
writeStrIL.Emit(OpCodes.Ldfld, yField);
writeStrIL.Emit(OpCodes.Box, typeof(int));
// Now, you have all of the arguments for your call to
// Console.WriteLine(string, object, object) atop the stack:
// the string InStr, a reference to the boxed value of 'x', and
// a reference to the boxed value of 'y'.
// Call Console.WriteLine(string, object, object) with EmitCall.
writeStrIL.EmitCall(OpCodes.Call, writeLineMI, null);
// Lastly, EmitWriteLine can also output the value of a field
// using the overload EmitWriteLine(FieldInfo).
writeStrIL.EmitWriteLine("The value of 'x' is:");
writeStrIL.EmitWriteLine(xField);
writeStrIL.EmitWriteLine("The value of 'y' is:");
writeStrIL.EmitWriteLine(yField);
// Since we return no value (void), the ret opcode will not
// return the top stack value.
writeStrIL.Emit(OpCodes.Ret);
return pointTypeBld.CreateType();
}
public static void Main() {
object[] ctorParams = new object[2];
Console.Write("Enter a integer value for X: ");
string myX = Console.ReadLine();
Console.Write("Enter a integer value for Y: ");
string myY = Console.ReadLine();
Console.WriteLine("---");
ctorParams[0] = Convert.ToInt32(myX);
ctorParams[1] = Convert.ToInt32(myY);
Type ptType = CreateDynamicType();
object ptInstance = Activator.CreateInstance(ptType, ctorParams);
ptType.InvokeMember("WritePoint",
BindingFlags.InvokeMethod,
null,
ptInstance,
new object[0]);
}
}
Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit
_
Class EmitWriteLineDemo
Public Shared Function CreateDynamicType() As Type
Dim ctorParams() As Type = {GetType(Integer), GetType(Integer)}
Dim myDomain As AppDomain = Thread.GetDomain()
Dim myAsmName As New AssemblyName()
myAsmName.Name = "MyDynamicAssembly"
Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave)
Dim pointModule As ModuleBuilder = myAsmBuilder.DefineDynamicModule("PointModule", "Point.dll")
Dim pointTypeBld As TypeBuilder = pointModule.DefineType("Point", _
TypeAttributes.Public)
Dim xField As FieldBuilder = pointTypeBld.DefineField("x", _
GetType(Integer), _
FieldAttributes.Public)
Dim yField As FieldBuilder = pointTypeBld.DefineField("y", _
GetType(Integer), _
FieldAttributes.Public)
Dim objType As Type = Type.GetType("System.Object")
Dim objCtor As ConstructorInfo = objType.GetConstructor(New Type(){})
Dim pointCtor As ConstructorBuilder = pointTypeBld.DefineConstructor( _
MethodAttributes.Public, _
CallingConventions.Standard, _
ctorParams)
Dim ctorIL As ILGenerator = pointCtor.GetILGenerator()
' First, you build the constructor.
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Call, objCtor)
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_1)
ctorIL.Emit(OpCodes.Stfld, xField)
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_2)
ctorIL.Emit(OpCodes.Stfld, yField)
ctorIL.Emit(OpCodes.Ret)
' Now, you'll build a method to output some information on the
' inside your dynamic class. This method will have the following
' definition in C#:
' Public Sub WritePoint()
Dim writeStrMthd As MethodBuilder = pointTypeBld.DefineMethod("WritePoint", _
MethodAttributes.Public, _
Nothing, Nothing)
Dim writeStrIL As ILGenerator = writeStrMthd.GetILGenerator()
' The below ILGenerator created demonstrates a few ways to create
' string output through STDIN.
' ILGenerator.EmitWriteLine(string) will generate a ldstr and a
' call to WriteLine for you.
writeStrIL.EmitWriteLine("The value of this current instance is:")
' Here, you will do the hard work yourself. First, you need to create
' the string we will be passing and obtain the correct WriteLine overload
' for said string. In the below case, you are substituting in two values,
' so the chosen overload is Console.WriteLine(string, object, object).
Dim inStr As [String] = "({0}, {1})"
Dim wlParams() As Type = {GetType(String), GetType(Object), GetType(Object)}
' We need the MethodInfo to pass into EmitCall later.
Dim writeLineMI As MethodInfo = GetType(Console).GetMethod("WriteLine", wlParams)
' Push the string with the substitutions onto the stack.
' This is the first argument for WriteLine - the string one.
writeStrIL.Emit(OpCodes.Ldstr, inStr)
' Since the second argument is an object, and it corresponds to
' to the substitution for the value of our integer field, you
' need to box that field to an object. First, push a reference
' to the current instance, and then push the value stored in
' field 'x'. We need the reference to the current instance (stored
' in local argument index 0) so Ldfld can load from the correct
' instance (this one).
writeStrIL.Emit(OpCodes.Ldarg_0)
writeStrIL.Emit(OpCodes.Ldfld, xField)
' Now, we execute the box opcode, which pops the value of field 'x',
' returning a reference to the integer value boxed as an object.
writeStrIL.Emit(OpCodes.Box, GetType(Integer))
' Atop the stack, you'll find our string inStr, followed by a reference
' to the boxed value of 'x'. Now, you need to likewise box field 'y'.
writeStrIL.Emit(OpCodes.Ldarg_0)
writeStrIL.Emit(OpCodes.Ldfld, yField)
writeStrIL.Emit(OpCodes.Box, GetType(Integer))
' Now, you have all of the arguments for your call to
' Console.WriteLine(string, object, object) atop the stack:
' the string InStr, a reference to the boxed value of 'x', and
' a reference to the boxed value of 'y'.
' Call Console.WriteLine(string, object, object) with EmitCall.
writeStrIL.EmitCall(OpCodes.Call, writeLineMI, Nothing)
' Lastly, EmitWriteLine can also output the value of a field
' using the overload EmitWriteLine(FieldInfo).
writeStrIL.EmitWriteLine("The value of 'x' is:")
writeStrIL.EmitWriteLine(xField)
writeStrIL.EmitWriteLine("The value of 'y' is:")
writeStrIL.EmitWriteLine(yField)
' Since we return no value (void), the ret opcode will not
' return the top stack value.
writeStrIL.Emit(OpCodes.Ret)
Return pointTypeBld.CreateType()
End Function 'CreateDynamicType
Public Shared Sub Main()
Dim ctorParams(1) As Object
Console.Write("Enter a integer value for X: ")
Dim myX As String = Console.ReadLine()
Console.Write("Enter a integer value for Y: ")
Dim myY As String = Console.ReadLine()
Console.WriteLine("---")
ctorParams(0) = Convert.ToInt32(myX)
ctorParams(1) = Convert.ToInt32(myY)
Dim ptType As Type = CreateDynamicType()
Dim ptInstance As Object = Activator.CreateInstance(ptType, ctorParams)
ptType.InvokeMember("WritePoint", _
BindingFlags.InvokeMethod, _
Nothing, ptInstance, Nothing)
End Sub
End Class
Remarks
The type of localBuilder must match the parameter type of an overload of the Console.WriteLine method.
Applies to
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