Type.IsGenericTypeDefinition プロパティとは何？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

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Type.IsGenericTypeDefinition プロパティ

メモ : このプロパティは、.NET Framework version 2.0 で新しく追加されたものです。

現在の Type が、他のジェネリック型を構築できるジェネリック型の定義を表しているかどうかを示す値を取得します。

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

Visual Basic (宣言)

Public Overridable ReadOnly
 Property IsGenericTypeDefinition As Boolean

Visual Basic (使用法)

Dim instance As Type
Dim value As Boolean

value = instance.IsGenericTypeDefinition

public virtual bool IsGenericTypeDefinition
 { get; }

C++

public:
virtual property bool IsGenericTypeDefinition {
    bool get ();
}

/** @property */
public boolean get_IsGenericTypeDefinition ()

JScript

public function get IsGenericTypeDefinition
 () : boolean

プロパティ値
Type オブジェクトがジェネリック型定義を表している場合は true。それ以外の場合は false。

解説

ジェネリック型定義は、他の型を構築するためのテンプレートです。たとえば、ジェネリック型定義 G<T> (C# 構文) (Visual Basic の場合は G(Of T)、C++ の場合は generic <typename T> ref class G) から、型 G<int> (Visual Basic の場合は G(Of Integer)) を構築できます。構築するには、Int32 型を含む汎用引数リストを指定して MakeGenericType メソッドを呼び出します。この構築型を表す Type オブジェクトの場合、GetGenericTypeDefinition メソッドはジェネリック型定義を再度取得します。

IsGenericTypeDefinition プロパティを使用して、現在の型から新しい型を作成できるかどうかを判断します。IsGenericTypeDefinition プロパティが true を返した場合は、MakeGenericType メソッドを呼び出して新しいジェネリック型を作成できます。

ジェネリックリフレクションで使用される用語の一定の条件の一覧については、IsGenericType のプロパティの解説を参照してください。

使用例

型がジェネリック型定義であるかどうかなど、型に関する情報を次の例に示します。構築型、ジェネリック型定義、および通常の型に対して情報が表示されています。

Visual Basic

Imports System
Imports System.Reflection
Imports System.Collections.Generic
Imports Microsoft.VisualBasic

Public Class Test
    Private Shared Sub DisplayGenericTypeInfo(ByVal
 t As Type) 
        Console.WriteLine(vbCrLf & t.ToString())
        
        Console.WriteLine(vbTab & "Is this a generic type
 definition? " _
            & t.IsGenericTypeDefinition)
        
        Console.WriteLine(vbTab & "Is it a generic type? "
 _
            & t.IsGenericType)
        
        If t.IsGenericType Then
            ' If this is a generic type, display the type arguments.
            '
            Dim typeArguments As Type() = t.GetGenericArguments()
            
            Console.WriteLine(vbTab & "List type arguments
 (" _
                & typeArguments.Length & "):")
            
            For Each tParam As
 Type In typeArguments
                ' If this is a type parameter, display its position.
                '
                If tParam.IsGenericParameter Then
                    Console.WriteLine(vbTab & vbTab & tParam.ToString() _
                        & vbTab & "(unassigned - parameter
 position " _
                        & tParam.GenericParameterPosition & ")")
                Else
                    Console.WriteLine(vbTab & vbTab & tParam.ToString())
                End If
            Next tParam
        End If
    
    End Sub 
    
    
    Public Shared Sub Main()
 
        Console.WriteLine(vbCrLf & "--- Display information
 about a constructed type, its")
        Console.WriteLine("    generic type definition, and an
 ordinary type.")
        
        ' Create a Dictionary of Test objects, using strings for the
        ' keys.       
        Dim d As New Dictionary(Of
 String, Test)()

        DisplayGenericTypeInfo(d.GetType())
        DisplayGenericTypeInfo(d.GetType().GetGenericTypeDefinition())
        
        ' Display information for an ordinary type.
        DisplayGenericTypeInfo(GetType(String))
    
    End Sub 'Main
End Class 'Test

' This example produces the following output:
'
'--- Display information about a constructed type, its
'    generic type definition, and an ordinary type.
'
'System.Collections.Generic.Dictionary[System.String, Test]
'        Is this a generic type definition? False
'        Is it a generic type? True
'        List type arguments (2):
'                System.String
'                Test
'
'System.Collections.Generic.Dictionary[TKey,TValue]
'        Is this a generic type definition? True
'        Is it a generic type? True
'        List type arguments (2):
'                TKey    (unassigned - parameter position 0)
'                TValue  (unassigned - parameter position 1)
'
'System.String
'        Is this a generic type definition? False
'        Is it a generic type? False

using System;
using System.Reflection;
using System.Collections.Generic;

public class Test
{
    private static void
 DisplayGenericTypeInfo(Type t)
    {
        Console.WriteLine("\r\n{0}", t);

        Console.WriteLine("\tIs this a generic type definition?
 {0}", 
            t.IsGenericTypeDefinition);

        Console.WriteLine("\tIs it a generic type? {0}", 
            t.IsGenericType);

        if (t.IsGenericType)
        {
            // If this is a generic type, display the type arguments.
            //
            Type[] typeArguments = t.GetGenericArguments();

            Console.WriteLine("\tList type arguments ({0}):", 
                typeArguments.Length);

            foreach (Type tParam in typeArguments)
            {
                // If this is a type parameter, display its
                // position.
                //
                if (tParam.IsGenericParameter)
                {
                    Console.WriteLine("\t\t{0}\t(unassigned - parameter position
 {1})",
                        tParam,
                        tParam.GenericParameterPosition);
                }
                else
                {
                    Console.WriteLine("\t\t{0}", tParam);
                }
            }
        }
    }

    public static void Main()
    {
        Console.WriteLine("\r\n--- Display information about a constructed type,
 its");
        Console.WriteLine("    generic type definition, and an ordinary type.");

        // Create a Dictionary of Test objects, using strings for the
        // keys.       
        Dictionary<string, Test> d = new
 Dictionary<string, Test>();

        // Display information for the constructed type and its generic
        // type definition.
        DisplayGenericTypeInfo(d.GetType());
        DisplayGenericTypeInfo(d.GetType().GetGenericTypeDefinition());

        // Display information for an ordinary type.
        DisplayGenericTypeInfo(typeof(string));
    }
}

/* This example produces the following output:

--- Display information about a constructed type, its
    generic type definition, and an ordinary type.

System.Collections.Generic.Dictionary[System.String,Test]
        Is this a generic type definition? False
        Is it a generic type? True
        List type arguments (2):
                System.String
                Test

System.Collections.Generic.Dictionary[TKey,TValue]
        Is this a generic type definition? True
        Is it a generic type? True
        List type arguments (2):
                TKey    (unassigned - parameter position 0)
                TValue  (unassigned - parameter position 1)

System.String
        Is this a generic type definition? False
        Is it a generic type? False
 */

C++

using namespace System;
using namespace System::Reflection;
using namespace System::Collections::Generic;

public ref class Test
{
private:
   static void DisplayGenericTypeInfo( Type^
 t )
   {
      Console::WriteLine( L"\r\n{0}", t );
      Console::WriteLine( L"\tIs this a generic type definition?
 {0}",
         t->IsGenericTypeDefinition );
      Console::WriteLine( L"\tIs it a generic type? {0}",
         t->IsGenericType );
      
      if ( t->IsGenericType )
      {
         
         // If this is a generic type, display the type arguments.
         //
         array<Type^>^typeArguments = t->GetGenericArguments();
         Console::WriteLine( L"\tList type arguments ({0}):",
            typeArguments->Length );
         System::Collections::IEnumerator^ myEnum =
            typeArguments->GetEnumerator();
         while ( myEnum->MoveNext() )
         {
            Type^ tParam = safe_cast<Type^>(myEnum->Current);
            
            // If this is a type parameter, display its
            // position.
            //
            if ( tParam->IsGenericParameter )
            {
               Console::WriteLine(
                  L"\t\t{0}\t(unassigned - parameter position {1})",
                  tParam, tParam->GenericParameterPosition );
            }
            else
            {
               Console::WriteLine( L"\t\t{0}", tParam );
            }
         }
      }
   }


public:
   static void Main()
   {
      Console::Write( L"\r\n--- Display information about a " );
      Console::WriteLine( L"constructed type, its" );
      Console::WriteLine( L"    generic type definition, and an ordinary type."
 );
      
      // Create a Dictionary of Test objects, using strings for the
      // keys.
      Dictionary< String^,Test^ >^ d = gcnew Dictionary< String^,Test^ >;
      
      // Display information for the constructed type and its generic
      // type definition.
      DisplayGenericTypeInfo( d->GetType() );
      DisplayGenericTypeInfo( d->GetType()->GetGenericTypeDefinition() );
      
      // Display information for an ordinary type.
      DisplayGenericTypeInfo( String::typeid );
   }

};

int main()
{
   Test::Main();
}

/* This example produces the following output:

--- Display information about a constructed type, its
    generic type definition, and an ordinary type.

System.Collections.Generic.Dictionary[System.String,Test]
        Is this a generic type definition? False
        Is it a generic type? True
        List type arguments (2):
                System.String
                Test

System.Collections.Generic.Dictionary[TKey,TValue]
        Is this a generic type definition? True
        Is it a generic type? True
        List type arguments (2):
                TKey    (unassigned - parameter position 0)
                TValue  (unassigned - parameter position 1)

System.String
        Is this a generic type definition? False
        Is it a generic type? False
 */

import System.*;
import System.Reflection.*;
import System.Collections.Generic.*;

public class Test
{
    private static void
 DisplayGenericTypeInfo(Type t)
    {
        Console.WriteLine("\r\n{0}", t);
        Console.WriteLine("\tIs this a generic type definition?
 {0}",
            (System.Boolean)t.get_IsGenericTypeDefinition());
        Console.WriteLine("\tDoes it have generic arguments? {0}",
            (System.Boolean)t.get_IsGenericType());
        if (t.get_IsGenericType()) {
            // If this is a generic type, display the type arguments.
            Type typeArguments[] = t.GetGenericArguments();
            Console.WriteLine("\tList type arguments ({0}):",
                (Int32)typeArguments.get_Length());
            for (int iCtr = 0; iCtr < typeArguments.get_Length();
 iCtr++) {
                Type tParam = typeArguments[iCtr];
                // If this is a type parameter, display its
                // position.
                
                if (tParam.get_IsGenericParameter()) {
                    Console.WriteLine("\t\t{0}\t(unassigned - parameter "
                        + "position {1})", tParam, 
                        (Int32)tParam.get_GenericParameterPosition());
                }
                else {
                    Console.WriteLine("\t\t{0}", tParam);
                }
            }
        }
    } //DisplayGenericTypeInfo

    public static void main(String[]
 args)
    {
        Console.WriteLine("\r\n--- Display information about a "
            + "constructed type, its");
        Console.WriteLine("    generic type definition, and an ordinary type.");
        // Create a Dictionary of Test objects, using strings for the
        // keys.       
        Dictionary<String,Test> d = new Dictionary<String
,Test>();
        // Display information for the constructed type and its generic
        // type definition.
        DisplayGenericTypeInfo(d.GetType());
        DisplayGenericTypeInfo(d.GetType().GetGenericTypeDefinition());
        // Display information for an ordinary type.
        DisplayGenericTypeInfo(String.class.ToType());
    } //main
} //Test

/* This example produces the following output:

--- Display information about a constructed type, its
    generic type definition, and an ordinary type.

System.Collections.Generic.Dictionary[System.String,Test]
        Is this a generic type definition? False
        Is it a generic type? True
        List type arguments (2):
                System.String
                Test

System.Collections.Generic.Dictionary[TKey,TValue]
        Is this a generic type definition? True
        Is it a generic type? True
        List type arguments (2):
                TKey    (unassigned - parameter position 0)
                TValue  (unassigned - parameter position 1)

System.String
        Is this a generic type definition? False
        Is it a generic type? False
 */

プラットフォーム

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0
.NET Compact Framework
サポート対象 : 2.0

参照

関連項目
Type クラス
Type メンバ
System 名前空間
Type.ContainsGenericParameters プロパティ
GetGenericTypeDefinition
その他の技術情報
リフレクションとジェネリック型
方法 : リフレクションを使用してジェネリック型をチェックおよびインスタンス化する

>> 「Type.IsGenericTypeDefinition プロパティ」を含む用語の索引
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Type.IsGenericTypeDefinition プロパティとは？ わかりやすく解説

Type.IsGenericTypeDefinition プロパティ

急上昇のことば

Type.IsGenericTypeDefinition プロパティとは？わかりやすく解説