ConditionalWeakTable<TKey,TValue>.Add(TKey, TValue) メソッド

定義

テーブルにキーを追加します。Adds a key to the table.

public:
 void Add(TKey key, TValue value);
public void Add (TKey key, TValue value);
member this.Add : 'Key * 'Value -> unit
Public Sub Add (key As TKey, value As TValue)

パラメーター

key
TKey

追加するキー。The key to add. key は、プロパティのアタッチ先となるオブジェクトを表します。key represents the object to which the property is attached.

value
TValue

キーのプロパティ値。The key's property value.

例外

keynull です。key is null.

key が既に存在します。key already exists.

次の例では、MainClass クラスと MainInfo クラスを定義しています。このクラスは、MainClass インスタンスに関する情報を提供します。The following example defines a MainClass class and a MainInfo class, which provides information about the MainClass instance. 次に、Add メソッドを呼び出して、MainClass オブジェクトとそれに関連付けられている MainInfo オブジェクトを ConditionalWeakTable<TKey,TValue> テーブルに追加します。The example then calls the Add method to add a MainClass object and its attached MainInfo object to a ConditionalWeakTable<TKey,TValue> table. この例では、GetOrCreateValue および GetValue メソッドを呼び出して、キー/値のペアをテーブルに追加する方法と、既存のキーの値を取得するための TryGetValue メソッドについても説明します。The example also illustrates calls to the GetOrCreateValue and GetValue methods to add key/value pairs to the table, and to the TryGetValue method to retrieve the value of an existing key.

using System;
using System.Reflection;
using System.Runtime.CompilerServices;

public class Example
{
   string Name; 
   
   public Example(string name)
   {
      this.Name = name;
   }
   
   public override string ToString()
   {
      return this.Name;
   }
}

// Define a class to contain information about each Example instance.
public class ExampleInfo
{
   public string Name;
   public int Methods;
   public int Properties;
   
   public override string ToString()
   {
      return String.Format("{0}: {1} Methods, {2} Properties", 
                           this.Name, this.Methods, this.Properties);
   }
}

public class ExampleTest
{
   private static BindingFlags flags = BindingFlags.Public | BindingFlags.Instance;

   public static void Main()
   {
      Example ex1 = new Example("ex1");
      Example ex2 = new Example("ex2");
      Example ex3 = new Example("ex3");
      
      ExampleInfo exInfo1 = new ExampleInfo(); 
      exInfo1.Name = ex1.ToString();
      exInfo1.Methods = ex1.GetType().GetMethods(flags).Length;
      exInfo1.Properties = ex1.GetType().GetProperties(flags).Length;
      
      ExampleInfo exInfo3 = new ExampleInfo(); 
      exInfo3.Name = ex3.ToString();
      exInfo3.Methods = ex3.GetType().GetMethods(flags).Length;
      exInfo3.Properties = ex3.GetType().GetProperties(flags).Length;

      var attached = new ConditionalWeakTable<Example, ExampleInfo>();
      ExampleInfo value = null;

      // Attach a property to ex1 using the Add method, then retrieve it.
      attached.Add(ex1, exInfo1);
      if (attached.TryGetValue(ex1, out value))
         Console.WriteLine("{0}, {1}", ex1, value);
      else
         Console.WriteLine("{0} does not have an attached property.", ex1);

      // Attempt to retrieve the value attached to ex2.
      value = attached.GetValue(ex2, ExampleTest.CreateAttachedValue);      
      if (attached.TryGetValue(ex2, out value))
         Console.WriteLine("{0}, {1}", ex2, value);
      else 
         Console.WriteLine("{0} does not have an attached property.", ex2);
      
      // Attempt to retrieve the value attached to ex3.
      value = attached.GetOrCreateValue(ex3);
      Console.WriteLine("{0}, {1}", ex3, value);
   }

   public static ExampleInfo CreateAttachedValue(Example ex)
   {
      ExampleInfo info = new ExampleInfo();
      info.Name = ex.ToString();
      info.Methods = ex.GetType().GetMethods(flags).Length;
      info.Properties = ex.GetType().GetProperties(flags).Length;
      return info;
   }
}
// The example displays the following output:
//       ex1, ex1: 4 Methods, 0 Properties
//       ex2, ex2: 4 Methods, 0 Properties
//       ex3, : 0 Methods, 0 Properties
Imports System.Reflection
Imports System.Runtime.CompilerServices

Public Class Example
   Public Name As String
   
   Public Sub New(name As String)
      Me.Name = name
   End Sub
   
   Public Overrides Function ToString() As String
      Return Me.Name
   End Function
End Class

' Define a class to contain information about each Example instance.
Public Class ExampleInfo
   Public Name As String
   Public Methods As Integer
   Public Properties As Integer
   
   Public Overrides Function ToString() As String
      Return String.Format("{0}: {1} Methods, {2} Properties", _
                           Me.Name, Me.Methods, Me.Properties)
   End Function
End Class

Module TestExample

   Private flags As BindingFlags = BindingFlags.Public Or BindingFlags.Instance

   Public Sub Main()
      Dim ex1 As New Example("ex1")
      Dim ex2 As New Example("ex2")
      Dim ex3 As New Example("ex3")
      
      Dim exInfo1 As New ExampleInfo() 
      exInfo1.Name = ex1.ToString()
      exInfo1.Methods = ex1.GetType().GetMethods(flags).Count
      exInfo1.Properties = ex1.GetType().GetProperties(flags).Count
      
      Dim exInfo3 As New ExampleInfo() 
      exInfo3.Name = ex3.ToString()
      exInfo3.Methods = ex3.GetType().GetMethods(flags).Count
      exInfo3.Properties = ex3.GetType().GetProperties(flags).Count

      Dim attached As New ConditionalWeakTable(Of Example, ExampleInfo)
      Dim value As ExampleInfo = Nothing

      ' Attach a property to ex1 using the Add method, then retrieve it.
      attached.Add(ex1, exInfo1)
      If attached.TryGetValue(ex1, value) Then
         Console.WriteLine("{0}, {1}", ex1, value)
      Else
         Console.WriteLine("{0} does not have an attached property.", ex1)
      End If

      ' Attempt to retrieve the value attached to ex2.
      value = attached.GetValue(ex2, AddressOf TestExample.CreateAttachedValue)      
      If attached.TryGetValue(ex2, value) Then
         Console.WriteLine("{0}, {1}", ex2, value)
      Else 
         Console.WriteLine("{0} does not have an attached property.", ex2)
      End If
      
      ' Atttempt to retrieve the value attached to ex3.
      value = attached.GetOrCreateValue(ex3)
      Console.WriteLine("{0}, {1}", ex3, value)
   End Sub
   
   Public Function CreateAttachedValue(ex As Example) As ExampleInfo
      Dim info As New ExampleInfo()
      info.Name = ex.ToString()
      info.Methods = ex.GetType().GetMethods(flags).Count
      info.Properties = ex.GetType().GetProperties(flags).Count
      Return info
   End Function
End Module
' The example displays the following output:
'       ex1, ex1: 4 Methods, 0 Properties
'       ex2, ex2: 4 Methods, 0 Properties
'       ex3, : 0 Methods, 0 Properties

注釈

ConditionalWeakTable<TKey,TValue> オブジェクト内のすべてのキーは一意である必要があります。Every key in a ConditionalWeakTable<TKey,TValue> object must be unique. キーは、同じオブジェクトを参照している場合は一意ではありません (つまり、Object.ReferenceEquals メソッドの引数として渡すと、trueを返します)。Keys are not unique if they refer to the same object (that is, if passing them as arguments to the Object.ReferenceEquals method returns true).

加算操作中にキーがガベージコレクトされると、既存のキーと値のペアが削除され、例外がスローされることなく新しいキーと値のペアが追加されます。If the key is garbage-collected during the addition operation, the existing key/value pair is removed and the new key/value pair is added without an exception being thrown.

適用対象

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