Como: Definir e executar métodos dinâmicos
Os procedimentos a seguir mostram como definir e executar um método dinâmico simples e um método dinâmico limite a uma instância de uma classe.Para obter mais informações sobre métodos dinâmicos, consulte o DynamicMethod classe e reflexão Emit dinâmico método Scenarios.
Para definir e executar um método dinâmico
Declare um tipo delegado para executar o método.Considere o uso de um delegado genérico para minimizar o número de tipos delegate que é necessário declarar.O seguinte código declara dois tipos de delegado que poderiam ser usados para o SquareIt método e um deles é genérica.
Private Delegate Function _ SquareItInvoker(ByVal input As Integer) As Long Private Delegate Function _ OneParameter(Of TReturn, TParameter0) _ (ByVal p0 As TParameter0) As TReturnprivate delegate long SquareItInvoker(int input); private delegate TReturn OneParameter<TReturn, TParameter0> (TParameter0 p0);private: delegate long long SquareItInvoker(int input); generic<typename TReturn, typename TParameter0> delegate TReturn OneParameter(TParameter0 p0);Crie uma matriz que especifica os tipos de parâmetro para o método dinâmico.Neste exemplo, o único parâmetro é um int (Integer no Visual Basic), portanto, o array tem apenas um elemento.
Dim methodArgs As Type() = { GetType(Integer) }Type[] methodArgs = {typeof(int)};array<Type^>^ methodArgs = { int::typeid };Crie um DynamicMethod.Neste exemplo, o método é chamado SquareIt.
.gif "Observação")
Observação:Não é necessário dar nomes de métodos dinâmicos, e não pode ser invocados pelo nome.Vários métodos dinâmicos podem ter o mesmo nome.No entanto, o nome aparece na telefonar empilha e pode ser útil para depuração.
O tipo do valor retornado é especificado sistema autônomo long. O método está associado com o módulo que contém o Example classe, que contém o código de exemplo. Qualquer módulo carregado pode ser especificado.Age do método dinâmico como um nível de módulo static método)Shared no Visual Basic).
Dim squareIt As New DynamicMethod( _ "SquareIt", _ GetType(Long), _ methodArgs, _ GetType(Example).Module)DynamicMethod squareIt = new DynamicMethod( "SquareIt", typeof(long), methodArgs, typeof(Example).Module);DynamicMethod^ squareIt = gcnew DynamicMethod( "SquareIt", long long::typeid, methodArgs, Example::typeid->Module);Emita o corpo do método.Neste exemplo, um ILGenerator o objeto é usado para emitir a Microsoft intermediate linguagem (MSIL). Como alternativa, um DynamicILInfo objeto pode ser usado em conjunto com geradores de código não gerenciado para emitir o corpo do método para um DynamicMethod.
O MSIL neste exemplo carrega o argumento, que é um int, na pilha, converte-o para um long, duplicatas do longe multiplica dois números. Isso deixa o resultado quadrado na pilha e tudo o método tem a fazer é retornado.
Dim il As ILGenerator = squareIt.GetILGenerator() il.Emit(OpCodes.Ldarg_0) il.Emit(OpCodes.Conv_I8) il.Emit(OpCodes.Dup) il.Emit(OpCodes.Mul) il.Emit(OpCodes.Ret)ILGenerator il = squareIt.GetILGenerator(); il.Emit(OpCodes.Ldarg_0); il.Emit(OpCodes.Conv_I8); il.Emit(OpCodes.Dup); il.Emit(OpCodes.Mul); il.Emit(OpCodes.Ret);ILGenerator^ il = squareIt->GetILGenerator(); il->Emit(OpCodes::Ldarg_0); il->Emit(OpCodes::Conv_I8); il->Emit(OpCodes::Dup); il->Emit(OpCodes::Mul); il->Emit(OpCodes::Ret);Criar uma instância do delegado (declarada na etapa 1) que representa o método dinâmico chamando o CreateDelegate método. Criar o delegado preenche o método e quaisquer outras tentativas de alterar o método — por exemplo, adicionando mais MSIL — são ignorados.O código a seguir cria o delegado e chama, usando um delegado genérico.
Dim invokeSquareIt As OneParameter(Of Long, Integer) = _ CType( _ squareIt.CreateDelegate( _ GetType(OneParameter(Of Long, Integer))), _ OneParameter(Of Long, Integer) _ ) Console.WriteLine("123456789 squared = {0}", _ invokeSquareIt(123456789))OneParameter<long, int> invokeSquareIt = (OneParameter<long, int>) squareIt.CreateDelegate(typeof(OneParameter<long, int>)); Console.WriteLine("123456789 squared = {0}", invokeSquareIt(123456789));OneParameter<long long, int>^ invokeSquareIt = (OneParameter<long long, int>^) squareIt->CreateDelegate(OneParameter<long long, int>::typeid); Console::WriteLine("123456789 squared = {0}", invokeSquareIt(123456789));
Para definir e executar um método dinâmico que esteja limite a um objeto
Declare um tipo delegado para executar o método.Considere o uso de um delegado genérico para minimizar o número de tipos delegate que é necessário declarar.O código a seguir declara um tipo delegado genérico que pode ser usado para executar qualquer método com um parâmetro e um valor retornado, ou um método com dois parâmetros e um valor retornado se o delegado é limite a um objeto.
Private Delegate Function _ OneParameter(Of TReturn, TParameter0) _ (ByVal p0 As TParameter0) As TReturnprivate delegate TReturn OneParameter<TReturn, TParameter0> (TParameter0 p0);generic<typename TReturn, typename TParameter0> delegate TReturn OneParameter(TParameter0 p0);Crie uma matriz que especifica os tipos de parâmetro para o método dinâmico.Se o delegado que representa o método deve ser vinculada a um objeto, o primeiro parâmetro deve corresponder ao tipo a que delegado está limite.Neste exemplo, há dois parâmetros, do tipo Example e digite int (Integer no Visual Basic).
Dim methodArgs2 As Type() = _ { GetType(Example), GetType(Integer) }Type[] methodArgs2 = { typeof(Example), typeof(int) };array<Type^>^ methodArgs2 = { Example::typeid, int::typeid };Crie um DynamicMethod.Neste exemplo do método não tem nome.O tipo do valor retornado é especificado sistema autônomo int (Integer no Visual Basic). O método tem acesso aos membros particulares e protegidos do Example classe.
Dim multiplyPrivate As New DynamicMethod( _ "", _ GetType(Integer), _ methodArgs2, _ GetType(Example))DynamicMethod multiplyHidden = new DynamicMethod( "", typeof(int), methodArgs2, typeof(Example));DynamicMethod^ multiplyHidden = gcnew DynamicMethod( "", int::typeid, methodArgs2, Example::typeid);Emita o corpo do método.Neste exemplo, um ILGenerator o objeto é usado para emitir a Microsoft intermediate linguagem (MSIL). Como alternativa, um DynamicILInfo objeto pode ser usado em conjunto com geradores de código não gerenciado para emitir o corpo do método para um DynamicMethod.
O MSIL neste exemplo carrega o primeiro argumento, o que é uma instância do Example classe e o usa para carregar o valor de um campo de instância particular do tipo int. O segundo argumento é carregado e os dois números são multiplicados.Se o resultado é maior que int, o valor é truncado e os bits mais significativos são descartados. O método retorna, com o valor retornado na pilha.
Dim ilMP As ILGenerator = multiplyPrivate.GetILGenerator() ilMP.Emit(OpCodes.Ldarg_0) Dim testInfo As FieldInfo = _ GetType(Example).GetField("test", _ BindingFlags.NonPublic Or BindingFlags.Instance) ilMP.Emit(OpCodes.Ldfld, testInfo) ilMP.Emit(OpCodes.Ldarg_1) ilMP.Emit(OpCodes.Mul) ilMP.Emit(OpCodes.Ret)ILGenerator ilMH = multiplyHidden.GetILGenerator(); ilMH.Emit(OpCodes.Ldarg_0); FieldInfo testInfo = typeof(Example).GetField("test", BindingFlags.NonPublic | BindingFlags.Instance); ilMH.Emit(OpCodes.Ldfld, testInfo); ilMH.Emit(OpCodes.Ldarg_1); ilMH.Emit(OpCodes.Mul); ilMH.Emit(OpCodes.Ret);ILGenerator^ ilMH = multiplyHidden->GetILGenerator(); ilMH->Emit(OpCodes::Ldarg_0); FieldInfo^ testInfo = Example::typeid->GetField("test", BindingFlags::NonPublic | BindingFlags::Instance); ilMH->Emit(OpCodes::Ldfld, testInfo); ilMH->Emit(OpCodes::Ldarg_1); ilMH->Emit(OpCodes::Mul); ilMH->Emit(OpCodes::Ret);Criar uma instância do delegado (declarada na etapa 1) que representa o método dinâmico chamando o CreateDelegate(Type, Object) sobrecarga de método. Criar o delegado preenche o método e quaisquer outras tentativas de alterar o método — por exemplo, adicionando mais MSIL — são ignorados.
Observação:Você pode chamar o CreateDelegate método várias vezes para criar delegados vinculados a outras instâncias do tipo de destino.
O código a seguir vincula o método a uma nova instância do Example classe cujo teste particular estiver definido como 42. Ou seja, sempre que o delegado é chamado a instância de Example é passado para o primeiro parâmetro do método.
O delegado OneParameter é usado como o primeiro parâmetro do método sempre recebe a instância do Example. Quando o delegado é chamado, somente o segundo parâmetro é necessário.
Dim invoke As OneParameter(Of Integer, Integer) = _ CType( _ multiplyPrivate.CreateDelegate( _ GetType(OneParameter(Of Integer, Integer)), _ new Example(42) _ ), _ OneParameter(Of Integer, Integer) _ ) Console.WriteLine("3 * test = {0}", invoke(3))OneParameter<int, int> invoke = (OneParameter<int, int>) multiplyHidden.CreateDelegate( typeof(OneParameter<int, int>), new Example(42) ); Console.WriteLine("3 * test = {0}", invoke(3));OneParameter<int, int>^ invoke = (OneParameter<int, int>^) multiplyHidden->CreateDelegate( OneParameter<int, int>::typeid, gcnew Example(42) ); Console::WriteLine("3 * test = {0}", invoke(3));
Exemplo
O exemplo de código a seguir demonstra um método dinâmico simples e um método dinâmico limite a uma instância de uma classe.
O método dinâmico simples tem um argumento, um inteiro de 32 bit e retorna o quadrado de 64 bit do que inteiro.Um delegado genérico é usado para chamar o método.
O segundo método dinâmico tem dois parâmetros, do tipo Example e digite int (Integer no Visual Basic). Quando o método dinâmico tiver sido criado, está limite a uma instância de Example, usando um delegado genérico que tem um argumento de tipo int. O delegado não tem um argumento do tipo Example como o primeiro parâmetro do método sempre recebe a instância do limite Example. Quando o delegado é chamado, somente o int argumento fornecido. Esse método dinâmico acessa um campo particular do Example classe e retorna o produto de campo particular e o int argumento.
O exemplo de código define delegados que podem ser usados para executar os métodos.
Imports System
Imports System.Reflection
Imports System.Reflection.Emit
Public Class Example
' The following constructor and private field are used to
' demonstrate a method bound to an object.
'
Private test As Integer
Public Sub New(ByVal test As Integer)
Me.test = test
End Sub
' Declare delegates that can be used to execute the completed
' SquareIt dynamic method. The OneParameter delegate can be
' used to execute any method with one parameter and a return
' value, or a method with two parameters and a return value
' if the delegate is bound to an object.
'
Private Delegate Function _
SquareItInvoker(ByVal input As Integer) As Long
Private Delegate Function _
OneParameter(Of TReturn, TParameter0) _
(ByVal p0 As TParameter0) As TReturn
Public Shared Sub Main()
' Example 1: A simple dynamic method.
'
' Create an array that specifies the parameter types for the
' dynamic method. In this example the only parameter is an
' Integer, so the array has only one element.
'
Dim methodArgs As Type() = { GetType(Integer) }
' Create a DynamicMethod. In this example the method is
' named SquareIt. It is not necessary to give dynamic
' methods names. They cannot be invoked by name, and two
' dynamic methods can have the same name. However, the
' name appears in calls stacks and can be useful for
' debugging.
'
' In this example the return type of the dynamic method
' is Long. The method is associated with the module that
' contains the Example class. Any loaded module could be
' specified. The dynamic method is like a module-level
' Shared method.
'
Dim squareIt As New DynamicMethod( _
"SquareIt", _
GetType(Long), _
methodArgs, _
GetType(Example).Module)
' Emit the method body. In this example ILGenerator is used
' to emit the MSIL. DynamicMethod has an associated type
' DynamicILInfo that can be used in conjunction with
' unmanaged code generators.
'
' The MSIL loads the argument, which is an Integer, onto the
' stack, converts the Integer to a Long, duplicates the top
' item on the stack, and multiplies the top two items on the
' stack. This leaves the squared number on the stack, and
' all the method has to do is return.
'
Dim il As ILGenerator = squareIt.GetILGenerator()
il.Emit(OpCodes.Ldarg_0)
il.Emit(OpCodes.Conv_I8)
il.Emit(OpCodes.Dup)
il.Emit(OpCodes.Mul)
il.Emit(OpCodes.Ret)
' Create a delegate that represents the dynamic method.
' Creating the delegate completes the method, and any further
' attempts to change the method (for example, by adding more
' MSIL) are ignored. The following code uses a generic
' delegate that can produce delegate types matching any
' single-parameter method that has a return type.
'
Dim invokeSquareIt As OneParameter(Of Long, Integer) = _
CType( _
squareIt.CreateDelegate( _
GetType(OneParameter(Of Long, Integer))), _
OneParameter(Of Long, Integer) _
)
Console.WriteLine("123456789 squared = {0}", _
invokeSquareIt(123456789))
' Example 2: A dynamic method bound to an instance.
'
' Create an array that specifies the parameter types for a
' dynamic method. If the delegate representing the method
' is to be bound to an object, the first parameter must
' match the type the delegate is bound to. In the following
' code the bound instance is of the Example class.
'
Dim methodArgs2 As Type() = _
{ GetType(Example), GetType(Integer) }
' Create a DynamicMethod. In this example the method has no
' name. The return type of the method is Integer. The method
' has access to the protected and private members of the
' Example class.
'
Dim multiplyPrivate As New DynamicMethod( _
"", _
GetType(Integer), _
methodArgs2, _
GetType(Example))
' Emit the method body. In this example ILGenerator is used
' to emit the MSIL. DynamicMethod has an associated type
' DynamicILInfo that can be used in conjunction with
' unmanaged code generators.
'
' The MSIL loads the first argument, which is an instance of
' the Example class, and uses it to load the value of a
' private instance field of type Integer. The second argument
' is loaded, and the two numbers are multiplied. If the result
' is larger than Integer, the value is truncated and the most
' significant bits are discarded. The method returns, with
' the return value on the stack.
'
Dim ilMP As ILGenerator = multiplyPrivate.GetILGenerator()
ilMP.Emit(OpCodes.Ldarg_0)
Dim testInfo As FieldInfo = _
GetType(Example).GetField("test", _
BindingFlags.NonPublic Or BindingFlags.Instance)
ilMP.Emit(OpCodes.Ldfld, testInfo)
ilMP.Emit(OpCodes.Ldarg_1)
ilMP.Emit(OpCodes.Mul)
ilMP.Emit(OpCodes.Ret)
' Create a delegate that represents the dynamic method.
' Creating the delegate completes the method, and any further
' attempts to change the method for example, by adding more
' MSIL are ignored.
'
' The following code binds the method to a new instance
' of the Example class whose private test field is set to 42.
' That is, each time the delegate is invoked the instance of
' Example is passed to the first parameter of the method.
'
' The delegate OneParameter is used, because the first
' parameter of the method receives the instance of Example.
' When the delegate is invoked, only the second parameter is
' required.
'
Dim invoke As OneParameter(Of Integer, Integer) = _
CType( _
multiplyPrivate.CreateDelegate( _
GetType(OneParameter(Of Integer, Integer)), _
new Example(42) _
), _
OneParameter(Of Integer, Integer) _
)
Console.WriteLine("3 * test = {0}", invoke(3))
End Sub
End Class
' This code example produces the following output:
'
'123456789 squared = 15241578750190521
'3 * test = 126
'
using System;
using System.Reflection;
using System.Reflection.Emit;
public class Example
{
// The following constructor and private field are used to
// demonstrate a method bound to an object.
private int test;
public Example(int test) { this.test = test; }
// Declare delegates that can be used to execute the completed
// SquareIt dynamic method. The OneParameter delegate can be
// used to execute any method with one parameter and a return
// value, or a method with two parameters and a return value
// if the delegate is bound to an object.
//
private delegate long SquareItInvoker(int input);
private delegate TReturn OneParameter<TReturn, TParameter0>
(TParameter0 p0);
public static void Main()
{
// Example 1: A simple dynamic method.
//
// Create an array that specifies the parameter types for the
// dynamic method. In this example the only parameter is an
// int, so the array has only one element.
//
Type[] methodArgs = {typeof(int)};
// Create a DynamicMethod. In this example the method is
// named SquareIt. It is not necessary to give dynamic
// methods names. They cannot be invoked by name, and two
// dynamic methods can have the same name. However, the
// name appears in calls stacks and can be useful for
// debugging.
//
// In this example the return type of the dynamic method
// is long. The method is associated with the module that
// contains the Example class. Any loaded module could be
// specified. The dynamic method is like a module-level
// static method.
//
DynamicMethod squareIt = new DynamicMethod(
"SquareIt",
typeof(long),
methodArgs,
typeof(Example).Module);
// Emit the method body. In this example ILGenerator is used
// to emit the MSIL. DynamicMethod has an associated type
// DynamicILInfo that can be used in conjunction with
// unmanaged code generators.
//
// The MSIL loads the argument, which is an int, onto the
// stack, converts the int to a long, duplicates the top
// item on the stack, and multiplies the top two items on the
// stack. This leaves the squared number on the stack, and
// all the method has to do is return.
//
ILGenerator il = squareIt.GetILGenerator();
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Conv_I8);
il.Emit(OpCodes.Dup);
il.Emit(OpCodes.Mul);
il.Emit(OpCodes.Ret);
// Create a delegate that represents the dynamic method.
// Creating the delegate completes the method, and any further
// attempts to change the method (for example, by adding more
// MSIL) are ignored. The following code uses a generic
// delegate that can produce delegate types matching any
// single-parameter method that has a return type.
//
OneParameter<long, int> invokeSquareIt =
(OneParameter<long, int>)
squareIt.CreateDelegate(typeof(OneParameter<long, int>));
Console.WriteLine("123456789 squared = {0}",
invokeSquareIt(123456789));
// Example 2: A dynamic method bound to an instance.
//
// Create an array that specifies the parameter types for a
// dynamic method. If the delegate representing the method
// is to be bound to an object, the first parameter must
// match the type the delegate is bound to. In the following
// code the bound instance is of the Example class.
//
Type[] methodArgs2 = { typeof(Example), typeof(int) };
// Create a DynamicMethod. In this example the method has no
// name. The return type of the method is int. The method
// has access to the protected and private data of the
// Example class.
//
DynamicMethod multiplyHidden = new DynamicMethod(
"",
typeof(int),
methodArgs2,
typeof(Example));
// Emit the method body. In this example ILGenerator is used
// to emit the MSIL. DynamicMethod has an associated type
// DynamicILInfo that can be used in conjunction with
// unmanaged code generators.
//
// The MSIL loads the first argument, which is an instance of
// the Example class, and uses it to load the value of a
// private instance field of type int. The second argument is
// loaded, and the two numbers are multiplied. If the result
// is larger than int, the value is truncated and the most
// significant bits are discarded. The method returns, with
// the return value on the stack.
//
ILGenerator ilMH = multiplyHidden.GetILGenerator();
ilMH.Emit(OpCodes.Ldarg_0);
FieldInfo testInfo = typeof(Example).GetField("test",
BindingFlags.NonPublic | BindingFlags.Instance);
ilMH.Emit(OpCodes.Ldfld, testInfo);
ilMH.Emit(OpCodes.Ldarg_1);
ilMH.Emit(OpCodes.Mul);
ilMH.Emit(OpCodes.Ret);
// Create a delegate that represents the dynamic method.
// Creating the delegate completes the method, and any further
// attempts to change the method for example, by adding more
// MSIL are ignored.
//
// The following code binds the method to a new instance
// of the Example class whose private test field is set to 42.
// That is, each time the delegate is invoked the instance of
// Example is passed to the first parameter of the method.
//
// The delegate OneParameter is used, because the first
// parameter of the method receives the instance of Example.
// When the delegate is invoked, only the second parameter is
// required.
//
OneParameter<int, int> invoke = (OneParameter<int, int>)
multiplyHidden.CreateDelegate(
typeof(OneParameter<int, int>),
new Example(42)
);
Console.WriteLine("3 * test = {0}", invoke(3));
}
}
/* This code example produces the following output:
123456789 squared = 15241578750190521
3 * test = 126
*/
using namespace System;
using namespace System::Reflection;
using namespace System::Reflection::Emit;
public ref class Example
{
// The following constructor and private field are used to
// demonstrate a method bound to an object.
private:
int test;
public:
Example(int test) { this->test = test; }
// Declare delegates that can be used to execute the completed
// SquareIt dynamic method. The OneParameter delegate can be
// used to execute any method with one parameter and a return
// value, or a method with two parameters and a return value
// if the delegate is bound to an object.
//
private:
delegate long long SquareItInvoker(int input);
generic<typename TReturn, typename TParameter0>
delegate TReturn OneParameter(TParameter0 p0);
public:
static void Main()
{
// Example 1: A simple dynamic method.
//
// Create an array that specifies the parameter types for the
// dynamic method. In this example the only parameter is an
// int, so the array has only one element.
//
array<Type^>^ methodArgs = { int::typeid };
// Create a DynamicMethod. In this example the method is
// named SquareIt. It is not necessary to give dynamic
// methods names. They cannot be invoked by name, and two
// dynamic methods can have the same name. However, the
// name appears in calls stacks and can be useful for
// debugging.
//
// In this example the return type of the dynamic method is
// long long. The method is associated with the module that
// contains the Example class. Any loaded module could be
// specified. The dynamic method is like a module-level
// static method.
//
DynamicMethod^ squareIt = gcnew DynamicMethod(
"SquareIt",
long long::typeid,
methodArgs,
Example::typeid->Module);
// Emit the method body. In this example ILGenerator is used
// to emit the MSIL. DynamicMethod has an associated type
// DynamicILInfo that can be used in conjunction with
// unmanaged code generators.
//
// The MSIL loads the argument, which is an int, onto the
// stack, converts the int to a long long, duplicates the top
// item on the stack, and multiplies the top two items on the
// stack. This leaves the squared number on the stack, and
// all the method has to do is return.
//
ILGenerator^ il = squareIt->GetILGenerator();
il->Emit(OpCodes::Ldarg_0);
il->Emit(OpCodes::Conv_I8);
il->Emit(OpCodes::Dup);
il->Emit(OpCodes::Mul);
il->Emit(OpCodes::Ret);
// Create a delegate that represents the dynamic method.
// Creating the delegate completes the method, and any further
// attempts to change the method (for example, by adding more
// MSIL) are ignored. The following code uses a generic
// delegate that can produce delegate types matching any
// single-parameter method that has a return type.
//
OneParameter<long long, int>^ invokeSquareIt =
(OneParameter<long long, int>^)
squareIt->CreateDelegate(OneParameter<long long, int>::typeid);
Console::WriteLine("123456789 squared = {0}",
invokeSquareIt(123456789));
// Example 2: A dynamic method bound to an instance.
//
// Create an array that specifies the parameter types for a
// dynamic method. If the delegate representing the method
// is to be bound to an object, the first parameter must
// match the type the delegate is bound to. In the following
// code the bound instance is of the Example class.
//
array<Type^>^ methodArgs2 = { Example::typeid, int::typeid };
// Create a DynamicMethod. In this example the method has no
// name. The return type of the method is int. The method
// has access to the protected and private data of the
// Example class.
//
DynamicMethod^ multiplyHidden = gcnew DynamicMethod(
"",
int::typeid,
methodArgs2,
Example::typeid);
// Emit the method body. In this example ILGenerator is used
// to emit the MSIL. DynamicMethod has an associated type
// DynamicILInfo that can be used in conjunction with
// unmanaged code generators.
//
// The MSIL loads the first argument, which is an instance of
// the Example class, and uses it to load the value of a
// private instance field of type int. The second argument is
// loaded, and the two numbers are multiplied. If the result
// is larger than int, the value is truncated and the most
// significant bits are discarded. The method returns, with
// the return value on the stack.
//
ILGenerator^ ilMH = multiplyHidden->GetILGenerator();
ilMH->Emit(OpCodes::Ldarg_0);
FieldInfo^ testInfo = Example::typeid->GetField("test",
BindingFlags::NonPublic | BindingFlags::Instance);
ilMH->Emit(OpCodes::Ldfld, testInfo);
ilMH->Emit(OpCodes::Ldarg_1);
ilMH->Emit(OpCodes::Mul);
ilMH->Emit(OpCodes::Ret);
// Create a delegate that represents the dynamic method.
// Creating the delegate completes the method, and any further
// attempts to change the method for example, by adding more
// MSIL are ignored.
//
// The following code binds the method to a new instance
// of the Example class whose private test field is set to 42.
// That is, each time the delegate is invoked the instance of
// Example is passed to the first parameter of the method.
//
// The delegate OneParameter is used, because the first
// parameter of the method receives the instance of Example.
// When the delegate is invoked, only the second parameter is
// required.
//
OneParameter<int, int>^ invoke = (OneParameter<int, int>^)
multiplyHidden->CreateDelegate(
OneParameter<int, int>::typeid,
gcnew Example(42)
);
Console::WriteLine("3 * test = {0}", invoke(3));
}
};
void main()
{
Example::Main();
}
/* This code example produces the following output:
123456789 squared = 15241578750190521
3 * test = 126
*/
Compilando o código
O código contém o translation from VPE for Csharp using () instruçõesImports no Visual Basic) necessário para compilação.
Nenhuma referência de assembly adicionais é necessária.
compilar o código na linha de comando usando csc.exe, vbc.exe ou cl.exe.Para compilar o código no Visual Studio, coloque-o em um modelo de projeto de aplicativo de console.
Consulte também
Conceitos
reflexão Emit dinâmico método Scenarios