Type.GetGenericTypeDefinition 方法

定義

命名空間:

System

組件:

System.Runtime.dll

來源:

Type.cs

傳回代表泛型類型定義的 Type 物件，利用此泛型類型定義就可以建構出目前的泛型類型。

public:
 virtual Type ^ GetGenericTypeDefinition();

public virtual Type GetGenericTypeDefinition ();

abstract member GetGenericTypeDefinition : unit -> Type
override this.GetGenericTypeDefinition : unit -> Type

Public Overridable Function GetGenericTypeDefinition () As Type

傳回

Type

代表泛型類型的 Type 物件，利用此泛型類型就可以建構出目前的類型。

例外狀況

InvalidOperationException

目前的類型不是泛型類型。 亦即，IsGenericType 會傳回 false。

NotSupportedException

基底類別不支援叫用的方法。 衍生類別必須提供實作。

範例

下列程式碼範例會使用一般實例建立來建立建構類型的實例，然後使用 GetType 和 GetGenericTypeDefinition 方法來擷取建構的類型和泛型型別定義。 這個範例會使用泛型 Dictionary<TKey,TValue> 型別;建構型別代表 Dictionary<TKey,TValue> 具有字串索引鍵之 Test 物件的 。

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

public ref class Test
{
public:
   static void Main()
   {
      Console::Write( L"\r\n--- Get the generic type that " );
      Console::WriteLine( L"defines a constructed type." );
     
      // Create a Dictionary of Test objects, using strings for the
      // keys.
      Dictionary< String^,Test^ >^ d = gcnew Dictionary< String^,Test^ >;
      
      // Get a Type object representing the constructed type.
      //
      Type^ constructed = d->GetType();
      DisplayTypeInfo( constructed );
      Type^ myGeneric = constructed->GetGenericTypeDefinition();
      DisplayTypeInfo( myGeneric );
   }

private:
   static void DisplayTypeInfo( 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 );
      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);
         Console::WriteLine( L"\t\t{0}", tParam );
      }
   }
};

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

/* This example produces the following output:

--- Get the generic type that defines a constructed type.

System.Collections.Generic.Dictionary`2[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`2[TKey,TValue]
        Is this a generic type definition? True
        Is it a generic type? True
        List type arguments (2):
                TKey
                TValue
 */

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

public class Test
{
    public static void Main()
    {
        Console.WriteLine("\r\n--- Get the generic type that defines a constructed type.");

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

        // Get a Type object representing the constructed type.
        //
        Type constructed = d.GetType();
        DisplayTypeInfo(constructed);

        Type generic = constructed.GetGenericTypeDefinition();
        DisplayTypeInfo(generic);
    }

    private static void DisplayTypeInfo(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);
        Type[] typeArguments = t.GetGenericArguments();
        Console.WriteLine("\tList type arguments ({0}):", typeArguments.Length);
        foreach (Type tParam in typeArguments)
        {
            Console.WriteLine("\t\t{0}", tParam);
        }
    }
}

/* This example produces the following output:

--- Get the generic type that defines a constructed type.

System.Collections.Generic.Dictionary`2[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`2[TKey,TValue]
        Is this a generic type definition? True
        Is it a generic type? True
        List type arguments (2):
                TKey
                TValue
 */

open System
open System.Collections.Generic

type Test() = class end

let displayTypeInfo (t: Type) =
    printfn $"\n{t}"
    printfn $"\tIs this a generic type definition? {t.IsGenericTypeDefinition}"
    printfn $"\tIs it a generic type? {t.IsGenericType}"
    let typeArguments = t.GetGenericArguments()
    printfn $"\tList type arguments ({typeArguments.Length}):"
    for tParam in typeArguments do
        printfn $"\t\t{tParam}"

printfn "\n--- Get the generic type that defines a constructed type."

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

// Get a Type object representing the constructed type.
let constructed = d.GetType()
displayTypeInfo constructed

let generic = constructed.GetGenericTypeDefinition()
displayTypeInfo generic


(* This example produces the following output:

--- Get the generic type that defines a constructed type.

System.Collections.Generic.Dictionary`2[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`2[TKey,TValue]
        Is this a generic type definition? True
        Is it a generic type? True
        List type arguments (2):
                TKey
                TValue
 *)

Imports System.Reflection
Imports System.Collections.Generic

Public Class Test
    Public Shared Sub Main() 
        Console.WriteLine(vbCrLf & "--- Get the generic type that defines a constructed type.")
        
        ' Create a Dictionary of Test objects, using strings for the
        ' keys.
        Dim d As New Dictionary(Of String, Test)
        
        ' Get a Type object representing the constructed type.
        '
        Dim constructed As Type = d.GetType()
        DisplayTypeInfo(constructed)
        
        Dim generic As Type = constructed.GetGenericTypeDefinition()
        DisplayTypeInfo(generic)
    End Sub
    
    Private Shared Sub DisplayTypeInfo(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)
        Dim typeArguments As Type() = t.GetGenericArguments()
        Console.WriteLine(vbTab & "List type arguments (" _
            & typeArguments.Length & "):")
        For Each tParam As Type In typeArguments
            Console.WriteLine(vbTab & vbTab & tParam.ToString())
        Next tParam
    End Sub
End Class

' This example produces the following output:
'
'--- Get the generic type that defines a constructed type.
'
'System.Collections.Generic.Dictionary`2[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`2[TKey,TValue]
'        Is this a generic type definition? True
'        Is it a generic type? True
'        List type arguments (2):
'                TKey
'                TValue
'

備註

泛型型別定義是可從中建構其他型別的範本。 例如，從以 C# 語法表示的泛型型別定義 G<T> (; G(Of T) 在 Visual Basic 或 generic <typename T> ref class G C++ 中) ，您可以建構和具現化 Visual Basic) 中的類型 G<int> (G(Of Integer) 。 假設物件 Type 代表這個建構型別，方法會 GetGenericTypeDefinition 傳回泛型型別定義。

如果使用相同的型別引數，從相同的泛型型別定義建立兩個建構型別，則 GetGenericTypeDefinition 方法會針對這兩種型別傳回相同的 Type 物件。

如果您在已經代表泛型型別定義的 物件上 Type 呼叫 GetGenericTypeDefinition 方法，它會傳回目前的 Type 。

重要

泛型型別的陣列本身不是泛型。 在 C# 程式碼或 Visual Basic 程式碼 A<int>[] v;Dim v() As A(Of Integer) 中，變數 v 的類型不是泛型。 在呼叫 GetGenericTypeDefinition 之前，使用 IsGenericType 來判斷類型是否為泛型。

如需泛型反映中所使用之規範的恆成立條件清單，請參閱 IsGenericType 屬性備註。

另請參閱

• MakeGenericType(Type[])
• ContainsGenericParameters
• IsGenericTypeDefinition
• 反映和泛用類型
• 如何：使用反映檢視和執行個體化泛型類型