DynamicMethod Classe

Definizione

public ref class DynamicMethod sealed : System::Reflection::MethodInfo

[System.Runtime.InteropServices.ComVisible(true)]
public sealed class DynamicMethod : System.Reflection.MethodInfo

public sealed class DynamicMethod : System.Reflection.MethodInfo

[<System.Runtime.InteropServices.ComVisible(true)>]
type DynamicMethod = class
    inherit MethodInfo

type DynamicMethod = class
    inherit MethodInfo

Public NotInheritable Class DynamicMethod
Inherits MethodInfo

Ereditarietà

Object

MemberInfo

MethodBase

MethodInfo

DynamicMethod

Attributi

ComVisibleAttribute

Esempio

Nell'esempio di codice seguente viene creato un metodo dinamico che accetta due parametri. Nell'esempio viene generato un corpo di funzione semplice che stampa il primo parametro nella console e l'esempio usa il secondo parametro come valore restituito del metodo. L'esempio completa il metodo creando un delegato, richiama il delegato con parametri diversi e infine richiama il metodo dinamico usando il Invoke metodo .

using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Globalization;

public class Test
{
    // Declare a delegate type that can be used to execute the completed
    // dynamic method.
    private delegate int HelloDelegate(string msg, int ret);

    public static void Main()
    {
        // Create an array that specifies the types of the parameters
        // of the dynamic method. This dynamic method has a String
        // parameter and an Integer parameter.
        Type[] helloArgs = {typeof(string), typeof(int)};

        // Create a dynamic method with the name "Hello", a return type
        // of Integer, and two parameters whose types are specified by
        // the array helloArgs. Create the method in the module that
        // defines the String class.
        DynamicMethod hello = new DynamicMethod("Hello",
            typeof(int),
            helloArgs,
            typeof(string).Module);

        // Create an array that specifies the parameter types of the
        // overload of Console.WriteLine to be used in Hello.
        Type[] writeStringArgs = {typeof(string)};
        // Get the overload of Console.WriteLine that has one
        // String parameter.
        MethodInfo writeString = typeof(Console).GetMethod("WriteLine",
            writeStringArgs);

        // Get an ILGenerator and emit a body for the dynamic method,
        // using a stream size larger than the IL that will be
        // emitted.
        ILGenerator il = hello.GetILGenerator(256);
        // Load the first argument, which is a string, onto the stack.
        il.Emit(OpCodes.Ldarg_0);
        // Call the overload of Console.WriteLine that prints a string.
        il.EmitCall(OpCodes.Call, writeString, null);
        // The Hello method returns the value of the second argument;
        // to do this, load the onto the stack and return.
        il.Emit(OpCodes.Ldarg_1);
        il.Emit(OpCodes.Ret);

        // Add parameter information to the dynamic method. (This is not
        // necessary, but can be useful for debugging.) For each parameter,
        // identified by position, supply the parameter attributes and a
        // parameter name.
        hello.DefineParameter(1, ParameterAttributes.In, "message");
        hello.DefineParameter(2, ParameterAttributes.In, "valueToReturn");

        // Create a delegate that represents the dynamic method. This
        // action completes the method. Any further attempts to
        // change the method are ignored.
        HelloDelegate hi =
            (HelloDelegate) hello.CreateDelegate(typeof(HelloDelegate));

        // Use the delegate to execute the dynamic method.
        Console.WriteLine("\r\nUse the delegate to execute the dynamic method:");
        int retval = hi("\r\nHello, World!", 42);
        Console.WriteLine("Invoking delegate hi(\"Hello, World!\", 42) returned: " + retval);

        // Execute it again, with different arguments.
        retval = hi("\r\nHi, Mom!", 5280);
        Console.WriteLine("Invoking delegate hi(\"Hi, Mom!\", 5280) returned: " + retval);

        Console.WriteLine("\r\nUse the Invoke method to execute the dynamic method:");
        // Create an array of arguments to use with the Invoke method.
        object[] invokeArgs = {"\r\nHello, World!", 42};
        // Invoke the dynamic method using the arguments. This is much
        // slower than using the delegate, because you must create an
        // array to contain the arguments, and value-type arguments
        // must be boxed.
        object objRet = hello.Invoke(null, BindingFlags.ExactBinding, null, invokeArgs, new CultureInfo("en-us"));
        Console.WriteLine("hello.Invoke returned: " + objRet);

        Console.WriteLine("\r\n ----- Display information about the dynamic method -----");
        // Display MethodAttributes for the dynamic method, set when
        // the dynamic method was created.
        Console.WriteLine("\r\nMethod Attributes: {0}", hello.Attributes);

        // Display the calling convention of the dynamic method, set when the
        // dynamic method was created.
        Console.WriteLine("\r\nCalling convention: {0}", hello.CallingConvention);

        // Display the declaring type, which is always null for dynamic
        // methods.
        if (hello.DeclaringType == null)
        {
            Console.WriteLine("\r\nDeclaringType is always null for dynamic methods.");
        }
        else
        {
            Console.WriteLine("DeclaringType: {0}", hello.DeclaringType);
        }

        // Display the default value for InitLocals.
        if (hello.InitLocals)
        {
            Console.Write("\r\nThis method contains verifiable code.");
        }
        else
        {
            Console.Write("\r\nThis method contains unverifiable code.");
        }
        Console.WriteLine(" (InitLocals = {0})", hello.InitLocals);

        // Display the module specified when the dynamic method was created.
        Console.WriteLine("\r\nModule: {0}", hello.Module);

        // Display the name specified when the dynamic method was created.
        // Note that the name can be blank.
        Console.WriteLine("\r\nName: {0}", hello.Name);

        // For dynamic methods, the reflected type is always null.
        if (hello.ReflectedType == null)
        {
            Console.WriteLine("\r\nReflectedType is null.");
        }
        else
        {
            Console.WriteLine("\r\nReflectedType: {0}", hello.ReflectedType);
        }

        if (hello.ReturnParameter == null)
        {
            Console.WriteLine("\r\nMethod has no return parameter.");
        }
        else
        {
            Console.WriteLine("\r\nReturn parameter: {0}", hello.ReturnParameter);
        }

        // If the method has no return type, ReturnType is System.Void.
        Console.WriteLine("\r\nReturn type: {0}", hello.ReturnType);

        // ReturnTypeCustomAttributes returns an ICustomeAttributeProvider
        // that can be used to enumerate the custom attributes of the
        // return value. At present, there is no way to set such custom
        // attributes, so the list is empty.
        if (hello.ReturnType == typeof(void))
        {
            Console.WriteLine("The method has no return type.");
        }
        else
        {
            ICustomAttributeProvider caProvider = hello.ReturnTypeCustomAttributes;
            object[] returnAttributes = caProvider.GetCustomAttributes(true);
            if (returnAttributes.Length == 0)
            {
                Console.WriteLine("\r\nThe return type has no custom attributes.");
            }
            else
            {
                Console.WriteLine("\r\nThe return type has the following custom attributes:");
                foreach( object attr in returnAttributes )
                {
                    Console.WriteLine("\t{0}", attr.ToString());
                }
            }
        }

        Console.WriteLine("\r\nToString: {0}", hello.ToString());

        // Display parameter information.
        ParameterInfo[] parameters = hello.GetParameters();
        Console.WriteLine("\r\nParameters: name, type, ParameterAttributes");
        foreach( ParameterInfo p in parameters )
        {
            Console.WriteLine("\t{0}, {1}, {2}",
                p.Name, p.ParameterType, p.Attributes);
        }
    }
}

/* This code example produces the following output:

Use the delegate to execute the dynamic method:

Hello, World!
Invoking delegate hi("Hello, World!", 42) returned: 42

Hi, Mom!
Invoking delegate hi("Hi, Mom!", 5280) returned: 5280

Use the Invoke method to execute the dynamic method:

Hello, World!
hello.Invoke returned: 42

 ----- Display information about the dynamic method -----

Method Attributes: PrivateScope, Public, Static

Calling convention: Standard

DeclaringType is always null for dynamic methods.

This method contains verifiable code. (InitLocals = True)

Module: CommonLanguageRuntimeLibrary

Name: Hello

ReflectedType is null.

Method has no return parameter.

Return type: System.Int32

The return type has no custom attributes.

ToString: Int32 Hello(System.String, Int32)

Parameters: name, type, ParameterAttributes
        message, System.String, In
        valueToReturn, System.Int32, In
 */

Imports System.Reflection
Imports System.Reflection.Emit
Imports System.Globalization

Public Class Test
    ' Declare a delegate type that can be used to execute the completed
    ' dynamic method. 
    Private Delegate Function HelloDelegate(ByVal msg As String, _
        ByVal ret As Integer) As Integer

    Public Shared Sub Main()
        ' Create an array that specifies the types of the parameters
        ' of the dynamic method. This dynamic method has a String
        ' parameter and an Integer parameter.
        Dim helloArgs() As Type = {GetType(String), GetType(Integer)}

        ' Create a dynamic method with the name "Hello", a return type
        ' of Integer, and two parameters whose types are specified by
        ' the array helloArgs. Create the method in the module that
        ' defines the String class.
        Dim hello As New DynamicMethod("Hello", _
            GetType(Integer), _
            helloArgs, _
            GetType(String).Module)

        ' Create an array that specifies the parameter types of the
        ' overload of Console.WriteLine to be used in Hello.
        Dim writeStringArgs() As Type = {GetType(String)}
        ' Get the overload of Console.WriteLine that has one
        ' String parameter.
        Dim writeString As MethodInfo = GetType(Console). _
            GetMethod("WriteLine", writeStringArgs) 

        ' Get an ILGenerator and emit a body for the dynamic method,
        ' using a stream size larger than the IL that will be
        ' emitted.
        Dim il As ILGenerator = hello.GetILGenerator(256)
        ' Load the first argument, which is a string, onto the stack.
        il.Emit(OpCodes.Ldarg_0)
        ' Call the overload of Console.WriteLine that prints a string.
        il.EmitCall(OpCodes.Call, writeString, Nothing)
        ' The Hello method returns the value of the second argument;
        ' to do this, load the onto the stack and return.
        il.Emit(OpCodes.Ldarg_1)
        il.Emit(OpCodes.Ret)

        ' Add parameter information to the dynamic method. (This is not
        ' necessary, but can be useful for debugging.) For each parameter,
        ' identified by position, supply the parameter attributes and a 
        ' parameter name.
        hello.DefineParameter(1, ParameterAttributes.In, "message")
        hello.DefineParameter(2, ParameterAttributes.In, "valueToReturn")

        ' Create a delegate that represents the dynamic method. This
        ' action completes the method. Any further attempts to
        ' change the method are ignored.
    Dim hi As HelloDelegate = _
            CType(hello.CreateDelegate(GetType(HelloDelegate)), HelloDelegate)

        ' Use the delegate to execute the dynamic method.
        Console.WriteLine(vbCrLf & "Use the delegate to execute the dynamic method:")
        Dim retval As Integer = hi(vbCrLf & "Hello, World!", 42)
        Console.WriteLine("Invoking delegate hi(""Hello, World!"", 42) returned: " _
            & retval & ".")

        ' Execute it again, with different arguments.
        retval = hi(vbCrLf & "Hi, Mom!", 5280)
        Console.WriteLine("Invoking delegate hi(""Hi, Mom!"", 5280) returned: " _
            & retval & ".")

        Console.WriteLine(vbCrLf & "Use the Invoke method to execute the dynamic method:")
        ' Create an array of arguments to use with the Invoke method.
        Dim invokeArgs() As Object = {vbCrLf & "Hello, World!", 42}
        ' Invoke the dynamic method using the arguments. This is much
        ' slower than using the delegate, because you must create an
        ' array to contain the arguments, and value-type arguments
        ' must be boxed.
        Dim objRet As Object = hello.Invoke(Nothing, _
            BindingFlags.ExactBinding, Nothing, invokeArgs, _
            New CultureInfo("en-us"))
        Console.WriteLine("hello.Invoke returned: {0}", objRet)

        Console.WriteLine(vbCrLf & _
            " ----- Display information about the dynamic method -----")
        ' Display MethodAttributes for the dynamic method, set when 
        ' the dynamic method was created.
        Console.WriteLine(vbCrLf & "Method Attributes: {0}", _
            hello.Attributes)

        ' Display the calling convention of the dynamic method, set when the 
        ' dynamic method was created.
        Console.WriteLine(vbCrLf & "Calling convention: {0}", _ 
            hello.CallingConvention)

        ' Display the declaring type, which is always Nothing for dynamic
        ' methods.
        If hello.DeclaringType Is Nothing Then
            Console.WriteLine(vbCrLf & "DeclaringType is always Nothing for dynamic methods.")
        Else
            Console.WriteLine("DeclaringType: {0}", hello.DeclaringType)
        End If

        ' Display the default value for InitLocals.
        If hello.InitLocals Then
            Console.Write(vbCrLf & "This method contains verifiable code.")
        Else
            Console.Write(vbCrLf & "This method contains unverifiable code.")
        End If
        Console.WriteLine(" (InitLocals = {0})", hello.InitLocals)

        ' Display the module specified when the dynamic method was created.
        Console.WriteLine(vbCrLf & "Module: {0}", hello.Module)

        ' Display the name specified when the dynamic method was created.
        ' Note that the name can be blank.
        Console.WriteLine(vbCrLf & "Name: {0}", hello.Name)

        ' For dynamic methods, the reflected type is always Nothing.
        If hello.ReflectedType Is Nothing Then
            Console.WriteLine(vbCrLf & "ReflectedType is Nothing.")
        Else
            Console.WriteLine(vbCrLf & "ReflectedType: {0}", _
                hello.ReflectedType)
        End If

        If hello.ReturnParameter Is Nothing Then
            Console.WriteLine(vbCrLf & "Method has no return parameter.")
        Else
            Console.WriteLine(vbCrLf & "Return parameter: {0}", _
                hello.ReturnParameter)
        End If

        ' If the method has no return type, ReturnType is System.Void.
        Console.WriteLine(vbCrLf & "Return type: {0}", hello.ReturnType)           

        ' ReturnTypeCustomAttributes returns an ICustomeAttributeProvider
        ' that can be used to enumerate the custom attributes of the
        ' return value. At present, there is no way to set such custom
        ' attributes, so the list is empty.
        If hello.ReturnType Is GetType(System.Void) Then
            Console.WriteLine("The method has no return type.")
        Else
            Dim caProvider As ICustomAttributeProvider = _
                hello.ReturnTypeCustomAttributes
            Dim returnAttributes() As Object = _
                caProvider.GetCustomAttributes(True)
            If returnAttributes.Length = 0 Then
                Console.WriteLine(vbCrLf _
                    & "The return type has no custom attributes.")
            Else
                Console.WriteLine(vbCrLf _
                    & "The return type has the following custom attributes:")
                For Each attr As Object In returnAttributes
                    Console.WriteLine(vbTab & attr.ToString())
                Next attr
            End If
        End If

        Console.WriteLine(vbCrLf & "ToString: " & hello.ToString())

        ' Display parameter information.
        Dim parameters() As ParameterInfo = hello.GetParameters()
        Console.WriteLine(vbCrLf & "Parameters: name, type, ParameterAttributes")
        For Each p As ParameterInfo In parameters
            Console.WriteLine(vbTab & "{0}, {1}, {2}", _ 
                p.Name, p.ParameterType, p.Attributes)
        Next p
    End Sub
End Class

' This code example produces the following output:
'
'Use the delegate to execute the dynamic method:
'
'Hello, World!
'Invoking delegate hi("Hello, World!", 42) returned: 42.
'
'Hi, Mom!
'Invoking delegate hi("Hi, Mom!", 5280) returned: 5280.
'
'Use the Invoke method to execute the dynamic method:
'
'Hello, World!
'hello.Invoke returned: 42
'
' ----- Display information about the dynamic method -----
'
'Method Attributes: PrivateScope, Public, Static
'
'Calling convention: Standard
'
'DeclaringType is always Nothing for dynamic methods.
'
'This method contains verifiable code. (InitLocals = True)
'
'Module: CommonLanguageRuntimeLibrary
'
'Name: Hello
'
'ReflectedType is Nothing.
'
'Method has no return parameter.
'
'Return type: System.Int32
'
'The return type has no custom attributes.
'
'ToString: Int32 Hello(System.String, Int32)
'
'Parameters: name, type, ParameterAttributes
'        message, System.String, In
'        valueToReturn, System.Int32, In

Commenti

Per altre informazioni su questa API, vedere Osservazioni supplementari sull'API per DynamicMethod.

Vedi anche

• Procedura: Definire ed eseguire metodi dinamici
• problemi di sicurezza in Reflection Emit
• Procedura dettagliata: Creazione di codice in scenari di attendibilità parziale