Anvisningar: Definiera och köra dynamiska metoder

Artikel
03/30/2024

Följande procedurer visar hur du definierar och kör en enkel dynamisk metod och en dynamisk metod som är bunden till en instans av en klass. Mer information om dynamiska metoder finns i DynamicMethod klassen .

Deklarera en ombudstyp för att köra metoden. Överväg att använda ett allmänt ombud för att minimera antalet ombudstyper som du behöver deklarera. Följande kod deklarerar två ombudstyper som kan användas för SquareIt metoden och en av dem är generisk.

private: 
    delegate long long SquareItInvoker(int input);

    generic<typename TReturn, typename TParameter0> 
        delegate TReturn OneParameter(TParameter0 p0);

private delegate long SquareItInvoker(int input);

private delegate TReturn OneParameter<TReturn, TParameter0>
    (TParameter0 p0);

Private Delegate Function _
    SquareItInvoker(ByVal input As Integer) As Long

Private Delegate Function _
    OneParameter(Of TReturn, TParameter0) _
    (ByVal p0 As TParameter0) As TReturn

Skapa en matris som anger parametertyperna för den dynamiska metoden. I det här exemplet är den enda parametern en int (Integer i Visual Basic), så matrisen har bara ett element.
```
array<Type^>^ methodArgs = { int::typeid };
```
```
Type[] methodArgs = {typeof(int)};
```
```
Dim methodArgs As Type() = {GetType(Integer)}
```
Skapa en DynamicMethod. I det här exemplet heter SquareItmetoden .

Kommentar

Det är inte nödvändigt att ange namn på dynamiska metoder och de kan inte anropas med namn. Flera dynamiska metoder kan ha samma namn. Namnet visas dock i anropsstackar och kan vara användbart för felsökning.

Typen av returvärde anges som long. Metoden är associerad med modulen som innehåller Example klassen, som innehåller exempelkoden. Alla inlästa moduler kan anges. Den dynamiska metoden fungerar som en metod på modulnivå static (Shared i Visual Basic).
```
DynamicMethod^ squareIt = gcnew DynamicMethod(
    "SquareIt", 
    long long::typeid, 
    methodArgs, 
    Example::typeid->Module);
```
```
DynamicMethod squareIt = new DynamicMethod(
    "SquareIt",
    typeof(long),
    methodArgs,
    typeof(Example).Module);
```
```
Dim squareIt As New DynamicMethod( _
    "SquareIt", _
    GetType(Long), _
    methodArgs, _
    GetType(Example).Module)
```
Avge metodtexten. I det här exemplet används ett ILGenerator objekt för att generera det gemensamma mellanliggande språket (CIL). Alternativt kan ett DynamicILInfo objekt användas tillsammans med ohanterade kodgeneratorer för att generera metodtexten för en DynamicMethod.

CIL i det här exemplet läser in argumentet, som är en int, till stacken, konverterar den till en long, duplicerar longoch multiplicerar de två talen. Detta lämnar det kvadratiska resultatet på stacken, och allt metoden behöver göra är att returnera.
```
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);
```
```
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)
```

Skapa en instans av ombudet (deklarerat i steg 1) som representerar den dynamiska metoden genom att anropa CreateDelegate metoden. När du skapar ombudet slutförs metoden och eventuella ytterligare försök att ändra metoden , till exempel att lägga till fler CIL, ignoreras. Följande kod skapar ombudet och anropar det med hjälp av ett allmänt ombud.

OneParameter<long long, int>^ invokeSquareIt = 
    (OneParameter<long long, int>^)
    squareIt->CreateDelegate(OneParameter<long long, int>::typeid);

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));

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))

Deklarera en ombudstyp för att köra metoden. Överväg att använda ett allmänt ombud för att minimera antalet ombudstyper som du behöver deklarera. Följande kod deklarerar en allmän ombudstyp som kan användas för att köra valfri metod med en parameter och ett returvärde, eller en metod med två parametrar och ett returvärde om ombudet är bundet till ett objekt.
```
generic<typename TReturn, typename TParameter0> 
    delegate TReturn OneParameter(TParameter0 p0);
```
```
private delegate TReturn OneParameter<TReturn, TParameter0>
    (TParameter0 p0);
```
```
Private Delegate Function _
    OneParameter(Of TReturn, TParameter0) _
    (ByVal p0 As TParameter0) As TReturn
```
Skapa en matris som anger parametertyperna för den dynamiska metoden. Om ombudet som representerar metoden ska bindas till ett objekt måste den första parametern matcha den typ som ombudet är bundet till. I det här exemplet finns det två parametrar av typen Example och typen int (Integer i Visual Basic).
```
array<Type^>^ methodArgs2 = { Example::typeid, int::typeid };
```
```
Type[] methodArgs2 = { typeof(Example), typeof(int) };
```
```
Dim methodArgs2 As Type() = _
    {GetType(Example), GetType(Integer)}
```

Skapa en DynamicMethod. I det här exemplet har metoden inget namn. Typen av returvärde anges som int (Integer i Visual Basic). Metoden har åtkomst till de privata och skyddade medlemmarna i Example klassen.

DynamicMethod^ multiplyHidden = gcnew DynamicMethod(
    "", 
    int::typeid, 
    methodArgs2, 
    Example::typeid);

DynamicMethod multiplyHidden = new DynamicMethod(
    "",
    typeof(int),
    methodArgs2,
    typeof(Example));

Dim multiplyPrivate As New DynamicMethod( _
    "", _
    GetType(Integer), _
    methodArgs2, _
    GetType(Example))

Avge metodtexten. I det här exemplet används ett ILGenerator objekt för att generera det gemensamma mellanliggande språket (CIL). Alternativt kan ett DynamicILInfo objekt användas tillsammans med ohanterade kodgeneratorer för att generera metodtexten för en DynamicMethod.

CIL i det här exemplet läser in det första argumentet, som är en instans av Example klassen, och använder det för att läsa in värdet för ett privat instansfält av typen int. Det andra argumentet läses in och de två talen multipliceras. Om resultatet är större än inttrunkeras värdet och de viktigaste bitarna ignoreras. Metoden returnerar med returvärdet i stacken.

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);

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);

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)

Skapa en instans av ombudet (deklarerat i steg 1) som representerar den dynamiska metoden genom att anropa CreateDelegate(Type, Object) metodens överlagring. När du skapar ombudet slutförs metoden och eventuella ytterligare försök att ändra metoden, till exempel att lägga till fler CIL, ignoreras.

Kommentar

Du kan anropa CreateDelegate metoden flera gånger för att skapa ombud som är bundna till andra instanser av måltypen.

Följande kod binder metoden till en ny instans av Example klassen vars privata testfält är inställt på 42. Varje gång ombudet anropas skickas alltså instansen av Example till metodens första parameter.

Ombudet OneParameter används eftersom den första parametern för metoden alltid tar emot instansen av Example. När ombudet anropas krävs bara den andra parametern.
```
OneParameter<int, int>^ invoke = (OneParameter<int, int>^)
    multiplyHidden->CreateDelegate(
        OneParameter<int, int>::typeid, 
        gcnew Example(42)
    );

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));
```
```
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))
```

Exempel

I följande kodexempel visas en enkel dynamisk metod och en dynamisk metod som är bunden till en instans av en klass.

Den enkla dynamiska metoden tar ett argument, ett 32-bitars heltal, och returnerar 64-bitars kvadraten i det heltalet. Ett allmänt ombud används för att anropa metoden.

Den andra dynamiska metoden har två parametrar av typen Example och typen int (Integer i Visual Basic). När den dynamiska metoden har skapats är den bunden till en instans av , med hjälp av Exampleett allmänt ombud som har ett argument av typen int. Ombudet har inget argument av typen Example eftersom den första parametern i metoden alltid tar emot den bundna instansen av Example. När ombudet anropas anges endast int argumentet. Den här dynamiska metoden kommer åt ett privat fält i Example klassen och returnerar produkten för det privata fältet och int argumentet.

Kodexemplet definierar ombud som kan användas för att köra metoderna.

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
 */

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
 */

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
'

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