DynamicObject.TryInvokeMember(InvokeMemberBinder, Object[], Object) メソッド

定義

メンバーを呼び出す演算の実装を提供します。Provides the implementation for operations that invoke a member. DynamicObject クラスの派生クラスでこのメソッドをオーバーライドして、メソッドの呼び出しなどの演算の動的な動作を指定できます。Classes derived from the DynamicObject class can override this method to specify dynamic behavior for operations such as calling a method.

public:
 virtual bool TryInvokeMember(System::Dynamic::InvokeMemberBinder ^ binder, cli::array <System::Object ^> ^ args, [Runtime::InteropServices::Out] System::Object ^ % result);
public virtual bool TryInvokeMember (System.Dynamic.InvokeMemberBinder binder, object[] args, out object result);
abstract member TryInvokeMember : System.Dynamic.InvokeMemberBinder * obj[] * obj -> bool
override this.TryInvokeMember : System.Dynamic.InvokeMemberBinder * obj[] * obj -> bool
Public Overridable Function TryInvokeMember (binder As InvokeMemberBinder, args As Object(), ByRef result As Object) As Boolean

パラメーター

binder
InvokeMemberBinder

動的な演算に関する情報を提供します。Provides information about the dynamic operation. binder.Name プロパティは、動的演算の対象であるメンバーの名前を提供します。The binder.Name property provides the name of the member on which the dynamic operation is performed. たとえば、ステートメント sampleObject.SampleMethod(100) の場合 (sampleObjectDynamicObject クラスの派生クラスのインスタンス)、binder.Name は "SampleMethod" を返します。For example, for the statement sampleObject.SampleMethod(100), where sampleObject is an instance of the class derived from the DynamicObject class, binder.Name returns "SampleMethod". メンバー名で大文字と小文字を区別するかどうかを binder.IgnoreCase プロパティで指定します。The binder.IgnoreCase property specifies whether the member name is case-sensitive.

args
Object[]

呼び出し演算でオブジェクト メンバーに渡される引数。The arguments that are passed to the object member during the invoke operation. たとえば、ステートメント sampleObject.SampleMethod(100) の場合 (sampleObjectDynamicObject クラスから派生)、args[0] は 100 に等しくなります。For example, for the statement sampleObject.SampleMethod(100), where sampleObject is derived from the DynamicObject class, args[0] is equal to 100.

result
Object

メンバー呼び出しの結果。The result of the member invocation.

戻り値

操作が正常に終了した場合は true。それ以外の場合は falsetrue if the operation is successful; otherwise, false. このメソッドが false を返す場合、言語のランタイム バインダーによって動作が決まりますIf this method returns false, the run-time binder of the language determines the behavior. (ほとんどの場合、言語固有の実行時例外がスローされます)。(In most cases, a language-specific run-time exception is thrown.)

ディクショナリ内の値にアクセスするための別の構文を提供するとします。これsampleDictionary["Text"] = "Sample text"sampleDictionary("Text") = "Sample text"より、(Visual Basic で) をsampleDictionary.Text = "Sample text"記述するのではなく、を記述できます。Assume that you want to provide alternative syntax for accessing values in a dictionary, so that instead of writing sampleDictionary["Text"] = "Sample text" (sampleDictionary("Text") = "Sample text" in Visual Basic), you can write sampleDictionary.Text = "Sample text". また、このディクショナリのすべての標準辞書メソッドを呼び出すこともできます。Also, you want to be able to call all the standard dictionary methods on this dictionary.

DynamicDictionary クラスDynamicObjectから派生したクラスのコード例を次に示します。The following code example demonstrates the DynamicDictionary class, which is derived from the DynamicObject class. クラスDynamicDictionaryには、キーと値Dictionary<string, object>のペアDictionary(Of String, Object)を格納するための型 (Visual Basic) のオブジェクトが格納されます。The DynamicDictionary class contains an object of the Dictionary<string, object> type (Dictionary(Of String, Object) in Visual Basic) to store the key-value pairs. TryInvokeMemberメソッドをオーバーライドしてDictionary<TKey,TValue>クラスのメソッドをサポートし、メソッドTrySetMemberTryGetMemberメソッドをオーバーライドして新しい構文をサポートします。It overrides the TryInvokeMember method to support methods of the Dictionary<TKey,TValue> class and overrides the TrySetMember and TryGetMember methods to support the new syntax. また、すべてのPrintディクショナリキーと値を出力するメソッドも用意されています。It also provides a Print method, which prints out all dictionary keys and values.

// Add using System.Reflection;
// to the beginning of the file.

// The class derived from DynamicObject.
public class DynamicDictionary : DynamicObject
{
    // The inner dictionary.
    Dictionary<string, object> dictionary
        = new Dictionary<string, object>();

    // Getting a property.
    public override bool TryGetMember(
        GetMemberBinder binder, out object result)
    {
        return dictionary.TryGetValue(binder.Name, out result);
    }

    // Setting a property.
    public override bool TrySetMember(
        SetMemberBinder binder, object value)
    {
        dictionary[binder.Name] = value;
        return true;
    }

    // Calling a method.
    public override bool TryInvokeMember(
        InvokeMemberBinder binder, object[] args, out object result)
    {
        Type dictType = typeof(Dictionary<string, object>);
        try
        {
            result = dictType.InvokeMember(
                         binder.Name,
                         BindingFlags.InvokeMethod,
                         null, dictionary, args);
            return true;
        }
        catch
        {
            result = null;
            return false;
        }
    }

    // This methods prints out dictionary elements.
    public void Print()
    {
        foreach (var pair in dictionary)
            Console.WriteLine(pair.Key + " " + pair.Value);
        if (dictionary.Count == 0)
            Console.WriteLine("No elements in the dictionary.");
    }
}

class Program
{
    static void Main(string[] args)
    {
        // Creating a dynamic dictionary.
        dynamic person = new DynamicDictionary();

        // Adding new dynamic properties.
        // The TrySetMember method is called.
        person.FirstName = "Ellen";
        person.LastName = "Adams";

        // Calling a method defined in the DynmaicDictionary class.
        // The Print method is called.
        person.Print();

        Console.WriteLine(
            "Removing all the elements from the dictionary.");

        // Calling a method that is not defined in the DynamicDictionary class.
        // The TryInvokeMember method is called.
        person.Clear();

        // Calling the Print method again.
        person.Print();

        // The following statement throws an exception at run time.
        // There is no Sample method 
        // in the dictionary or in the DynamicDictionary class.
        // person.Sample();        
    }
}

// This example has the following output:

// FirstName Ellen 
// LastName Adams
// Removing all the elements from the dictionary.
// No elements in the dictionary.
' Add Imports System.Reflection
' to the beginning of the file.

' The class derived from DynamicObject.
Public Class DynamicDictionary
    Inherits DynamicObject

    ' The inner dictionary.
    Dim dictionary As New Dictionary(Of String, Object)

    ' Getting a property value.
    Public Overrides Function TryGetMember(
        ByVal binder As System.Dynamic.GetMemberBinder,
        ByRef result As Object) As Boolean

        Return dictionary.TryGetValue(binder.Name, result)
    End Function

    ' Setting a property value.
    Public Overrides Function TrySetMember(
        ByVal binder As System.Dynamic.SetMemberBinder,
        ByVal value As Object) As Boolean

        dictionary(binder.Name) = value
        Return True
    End Function


    ' Calling a method.
    Public Overrides Function TryInvokeMember(
        ByVal binder As System.Dynamic.InvokeMemberBinder,
        ByVal args() As Object, ByRef result As Object) As Boolean

        Dim dictType As Type = GetType(Dictionary(Of String, Object))
        Try
            result = dictType.InvokeMember(
                         binder.Name,
                         BindingFlags.InvokeMethod,
                         Nothing, dictionary, args)
            Return True
        Catch ex As Exception
            result = Nothing
            Return False
        End Try
    End Function

    ' This method prints out dictionary elements.
    Public Sub Print()
        For Each pair In dictionary
            Console.WriteLine(pair.Key & " " & pair.Value)
        Next
        If (dictionary.Count = 0) Then
            Console.WriteLine("No elements in the dictionary.")
        End If
    End Sub
End Class

Sub Test()
    ' Creating a dynamic dictionary.
    Dim person As Object = New DynamicDictionary()

    ' Adding new dynamic properties.
    ' The TrySetMember method is called.
    person.FirstName = "Ellen"
    person.LastName = "Adams"

    ' Calling a method defined in the DynmaicDictionary class.
    ' The Print method is called.
    person.Print()

    Console.WriteLine(
        "Removing all the elements from the dictionary.")

    ' Calling a method that is not defined in the DynamicDictionary class.
    ' The TryInvokeMember method is called.
    person.Clear()

    ' Calling the Print method again.
    person.Print()

    ' The following statement throws an exception at run time.
    ' There is no Sample method 
    ' in the dictionary or in the DynamicDictionary class.
    ' person.Sample()
End Sub


' This example has the following output:

' FirstName Ellen 
' LastName Adams
' Removing all the elements from the dictionary.
' No elements in the dictionary.

注釈

DynamicObjectクラスから派生したクラスは、このメソッドをオーバーライドして、オブジェクトメンバーを呼び出す操作を動的オブジェクトに対して実行する方法を指定できます。Classes derived from the DynamicObject class can override this method to specify how operations that invoke an object member should be performed for a dynamic object. メソッドがオーバーライドされない場合、言語のランタイムバインダーによって動作が決まります。When the method is not overridden, the run-time binder of the language determines the behavior. (ほとんどの場合、言語固有の実行時例外がスローされます)。(In most cases, a language-specific run-time exception is thrown.)

このメソッドがオーバーライドされると、のようなsampleObject.SampleMethod(100)操作を実行すると自動的に呼び出されます。ここsampleObjectで、はDynamicObjectクラスから派生します。If this method is overridden, it is automatically invoked when you perform an operation like sampleObject.SampleMethod(100), where sampleObject is derived from the DynamicObject class.

DynamicObjectクラスから派生したクラスに独自のメソッドを追加することもできます。You can also add your own methods to classes that are derived from the DynamicObject class. たとえば、 TryInvokeMemberメソッドをオーバーライドすると、動的ディスパッチシステムは、指定されたメソッドがクラスに存在するかどうかを最初に判断しようとします。For example, if you override the TryInvokeMember method, the dynamic dispatch system first attempts to determine whether the specified method exists in the class. メソッドが見つからない場合は、 TryInvokeMember実装を使用します。If it does not find the method, it uses the TryInvokeMember implementation.

このメソッドは、およびrefパラメーター outをサポートしていません。This method does not support ref and out parameters. args配列内のすべてのパラメーターは、値によって渡されます。All parameters in the args array are passed by value.

適用対象