DynamicMethod クラスとは何？わかりやすく解説 Weblio辞書

.NET Framework クラスライブラリリファレンス

索引トップランキング

DynamicMethod クラス

メモ : このクラスは、.NET Framework version 2.0 で新しく追加されたものです。

動的メソッドを定義および表現します。このクラスは継承できません。

名前空間: System.Reflection.Emit
アセンブリ: mscorlib (mscorlib.dll 内)
構文

Visual Basic (宣言)

<ComVisibleAttribute(True)> _
Public NotInheritable Class
 DynamicMethod
    Inherits MethodInfo

Visual Basic (使用法)

Dim instance As DynamicMethod

[ComVisibleAttribute(true)] 
public sealed class DynamicMethod : MethodInfo

C++

[ComVisibleAttribute(true)] 
public ref class DynamicMethod sealed : public
 MethodInfo

/** @attribute ComVisibleAttribute(true) */ 
public final class DynamicMethod extends MethodInfo

JScript

ComVisibleAttribute(true) 
public final class DynamicMethod extends
 MethodInfo

解説

DynamicMethod クラスを使用すると、実行時にメソッドを生成し実行できます。メソッドを格納するために、動的アセンブリと動的型を生成する必要はありません。動的メソッドは、少量のコードを生成し実行するための最も効率的な方法です。

動的メソッドは、モジュールまたは型に論理的に関連付けられます。動的メソッドがモジュールに関連付けられている場合、そのモジュールに対して実質的にはグローバルです。十分なアクセス許可があれば、動的メソッドはジャストインタイム (JIT: Just-In-Time) の参照範囲チェックをスキップし、そのモジュール内で宣言されている型のプライベートデータにアクセスできます。開発者がそのモジュールを作成したかどうかに関係なく、動的メソッドはどのモジュールにでも関連付けることができます。

動的メソッドが型に関連付けられている場合、その型のプライベートメンバにアクセスできます。動的メソッドが同じモジュール内で宣言されている他の型のプライベートデータにアクセスしない場合は、JIT の参照範囲チェックをスキップする必要はありません。動的メソッドは、どの型にも関連付けることができます。

	モジュールに関連付けられている場合	型に関連付けられている場合
JIT の参照範囲チェック	パブリック型、内部型、プライベート型のパブリックメンバと内部メンバ。	関連付けられている型のすべてのメンバ。他のすべての型のパブリックメンバと内部メンバ。
JIT の参照範囲チェックのスキップ	すべての型のすべてのメンバ。	すべての型のすべてのメンバ。

動的メソッドは、関連付けられているモジュール、または関連付けられている型を格納するモジュールのアクセス許可を持ちます。

動的メソッドとそのパラメータには、名前を付ける必要はありませんが、名前を指定するとデバッグを行う際に役立ちます。動的メソッドまたはそのパラメータでは、カスタム属性はサポートされていません。

動的メソッドは static メソッド (Visual Basic では Shared メソッド) ですが、.NET Framework Version 2.0 に導入されているデリゲートバインディングの緩やかな規則では、動的メソッドをオブジェクトにバインドすることが許可されています。したがって、そのデリゲートインスタンスを使用して動的メソッドを呼び出した場合、インスタンスメソッドと同様に機能します。この例については、CreateDelegate(Type,Object) メソッドオーバーロードで説明しています。

使用例

2 つのパラメータを使用する動的メソッドを作成するコード例を次に示します。この例では、コンソールに 1 つ目のパラメータを出力する簡単な関数本体を出力し、2 つ目のパラメータをメソッドの戻り値として使用しています。この例では、デリゲートを作成することによってメソッドを完了し、さまざまなパラメータを持つデリゲートを呼び出し、最後に Invoke メソッドを使用して動的メソッドを呼び出します。

Visual Basic

Imports System
Imports System.Reflection
Imports System.Reflection.Emit
Imports Microsoft.VisualBasic
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)

        ' 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())

        ' 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.
        Dim parameter1 As ParameterBuilder
 = hello.DefineParameter( _
             1, ParameterAttributes.In, "message")
        Dim parameter2 As ParameterBuilder
 = hello.DefineParameter( _
             2, ParameterAttributes.In, "valueToReturn")

        ' 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

        ' Create a delegate that represents the dynamic method. This
        ' action completes the method, and any further attempts to
        ' change the method will cause an exception.
    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)
    End Sub
End Class

' This code example produces the following output:
'
'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
'
'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

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);

        // 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());

        // 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.
        ParameterBuilder parameter1 = hello.DefineParameter(
            1, 
            ParameterAttributes.In, 
            "message"
        );
        ParameterBuilder parameter2 = hello.DefineParameter(
            2, 
            ParameterAttributes.In, 
            "valueToReturn"
        );

        // 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);
        }

        // Create a delegate that represents the dynamic method. This
        // action completes the method, and any further attempts to
        // change the method will cause an exception.
        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);
    }
}

/* This code example produces the following output:

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

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
 */

継承階層

System.Object
   System.Reflection.MemberInfo
     System.Reflection.MethodBase
       System.Reflection.MethodInfo
        System.Reflection.Emit.DynamicMethod

スレッドセーフ

この型の public static (Visual Basic では Shared) メンバはすべて、スレッドセーフです。インスタンスメンバの場合は、スレッドセーフであるとは限りません。