Type.MakeGenericType(Type[]) Type.MakeGenericType(Type[]) Type.MakeGenericType(Type[]) Type.MakeGenericType(Type[]) Method

定義

用類型陣列的項目取代目前泛型類型定義的型別參數,並傳回代表所得結果建構類型的 Type 物件。Substitutes the elements of an array of types for the type parameters of the current generic type definition and returns a Type object representing the resulting constructed type.

public:
 virtual Type ^ MakeGenericType(... cli::array <Type ^> ^ typeArguments);
public virtual Type MakeGenericType (params Type[] typeArguments);
abstract member MakeGenericType : Type[] -> Type
override this.MakeGenericType : Type[] -> Type
Public Overridable Function MakeGenericType (ParamArray typeArguments As Type()) As Type

參數

typeArguments
Type[]

由類型組成的陣列,用來取代目前泛型類型的類型參數。An array of types to be substituted for the type parameters of the current generic type.

傳回

Type,表示用 typeArguments 的項目取代目前泛型類型之類型參數所得到的建構類型。A Type representing the constructed type formed by substituting the elements of typeArguments for the type parameters of the current generic type.

例外狀況

目前類型不代表泛型型別定義。The current type does not represent a generic type definition. 亦即,IsGenericTypeDefinition 會傳回 falseThat is, IsGenericTypeDefinition returns false.

typeArgumentsnulltypeArguments is null.

-或--or- typeArguments 的項目是 nullAny element of typeArguments is null.

typeArguments 中的項目數和目前泛型型別定義的類型參數數目不同。The number of elements in typeArguments is not the same as the number of type parameters in the current generic type definition.

-或--or- typeArguments 的所有項目都不符合目前泛型型別的對應類型參數所指定的條件約束。Any element of typeArguments does not satisfy the constraints specified for the corresponding type parameter of the current generic type.

-或--or- typeArguments 包含的項目是指標類型 (IsPointer 傳回 true)、傳址類型 (IsByRef 傳回 true) 或 VoidtypeArguments contains an element that is a pointer type (IsPointer returns true), a by-ref type (IsByRef returns true), or Void.

基底類別不支援叫用的方法。The invoked method is not supported in the base class. 衍生類別必須提供實作。Derived classes must provide an implementation.

範例

下列範例會使用MakeGenericType方法用來建立建構的類型的泛型型別定義從Dictionary<TKey,TValue>型別。The following example uses the MakeGenericType method to create a constructed type from the generic type definition for the Dictionary<TKey,TValue> type. 建構的型別代表Dictionary<TKey,TValue>Test具有字串索引鍵的物件。The constructed type represents a Dictionary<TKey,TValue> of Test objects with string keys.

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

namespace Example
{
    public ref class Test
    {
    public:
        static void CreateConstructedType(void)
        {      
            Console::WriteLine("\r\n--- Create a constructed type"
                " from the generic Dictionary`2 type.");
            
            // Create a type object representing 
            // the generic Dictionary`2 type.
    	    Type^ genericType = Type::GetType(
                "System.Collections.Generic.Dictionary`2");
    	    if (genericType != nullptr)
    	    {  
    	        DisplayTypeInfo(genericType);
    	    }
    	    else
    	    {
    	        Console::WriteLine("The type is not found");
    	        return;
    	    }
            
            // Create an array of types to substitute for the type
            // parameters of Dictionary`2. 
            // The key is of type string, and the type to be 
            // contained in the Dictionary`2 is Test.
            array<Type^>^ typeArgs = {String::typeid, Test::typeid};
            Type^ constructedType = 
                genericType->MakeGenericType(typeArgs);
            DisplayTypeInfo(constructedType);
            
            // Compare the type objects obtained above to type objects
            // obtained using typeof() and GetGenericTypeDefinition().
            Console::WriteLine("\r\n--- Compare types obtained by"
                " different methods:");

    	    Type^ definedType = Dictionary<String^, Test^>::typeid;
            Console::WriteLine("\tAre the constructed types "
                "equal? {0}", definedType == constructedType);
            Console::WriteLine("\tAre the generic types equal? {0}", 
                definedType->GetGenericTypeDefinition() == genericType);
        }

    private:
        static void DisplayTypeInfo(Type^ typeToDisplay)
        {   
            Console::WriteLine("\r\n{0}", typeToDisplay);
            Console::WriteLine("\tIs this a generic type definition? "
                "{0}", typeToDisplay->IsGenericTypeDefinition);
            Console::WriteLine("\tIs it a generic type? "
                "{0}", typeToDisplay->IsGenericType);
            
            array<Type^>^ typeArguments = 
                typeToDisplay->GetGenericArguments();
            Console::WriteLine("\tList type arguments ({0}):", 
                typeArguments->Length);
            
            for each (Type^ typeArgument in typeArguments)
            {   
                Console::WriteLine("\t\t{0}", typeArgument);
            }
        }
    };
}

int main(void)
{
    Example::Test::CreateConstructedType();
}

/* This example produces the following output:

--- Create a constructed type from the generic Dictionary`2 type.

System.Collections.Generic.Dictionary`2[KeyType,ValueType]
          Is this a generic type definition? True
          Is it a generic type? True
          List type arguments (2):
                     K
                     V

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

--- Compare types obtained by different methods:
          Are the constructed types equal? True
          Are the generic types equal? True
 */
using System;
using System.Reflection;
using System.Collections.Generic;

public class Test
{
    public static void Main()
    {
        Console.WriteLine("\r\n--- Create a constructed type from the generic Dictionary type.");

        // Create a type object representing the generic Dictionary 
        // type, by omitting the type arguments (but keeping the 
        // comma that separates them, so the compiler can infer the
        // number of type parameters).      
        Type generic = typeof(Dictionary<,>);
        DisplayTypeInfo(generic);

        // Create an array of types to substitute for the type
        // parameters of Dictionary. The key is of type string, and
        // the type to be contained in the Dictionary is Test.
        Type[] typeArgs = { typeof(string), typeof(Test) };

        // Create a Type object representing the constructed generic
        // type.
        Type constructed = generic.MakeGenericType(typeArgs);
        DisplayTypeInfo(constructed);

        // Compare the type objects obtained above to type objects
        // obtained using typeof() and GetGenericTypeDefinition().
        Console.WriteLine("\r\n--- Compare types obtained by different methods:");

        Type t = typeof(Dictionary<String, Test>);
        Console.WriteLine("\tAre the constructed types equal? {0}", t == constructed);
        Console.WriteLine("\tAre the generic types equal? {0}", 
            t.GetGenericTypeDefinition() == 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:

--- Create a constructed type from the generic Dictionary type.

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

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

--- Compare types obtained by different methods:
        Are the constructed types equal? True
        Are the generic types equal? True
 */
Imports System
Imports System.Reflection
Imports System.Collections.Generic
Imports Microsoft.VisualBasic

Public Class Test
    Public Shared Sub Main()
        Console.WriteLine(vbCrLf & "--- Create a constructed type from the generic Dictionary type.")

        ' Create a type object representing the generic Dictionary 
        ' type, by omitting the type arguments (but keeping the 
        ' comma that separates them, so the compiler can infer the
        ' number of type parameters).
        Dim generic As Type = GetType(Dictionary(Of ,))
        DisplayTypeInfo(generic)

        ' Create an array of types to substitute for the type
        ' parameters of Dictionary. The key is of type string, and
        ' the type to be contained in the Dictionary is Test.
        Dim typeArgs() As Type = { GetType(String), GetType(Test) }

        ' Create a Type object representing the constructed generic
        ' type.
        Dim constructed As Type = generic.MakeGenericType(typeArgs)
        DisplayTypeInfo(constructed)

        ' Compare the type objects obtained above to type objects
        ' obtained using GetType() and GetGenericTypeDefinition().
        Console.WriteLine(vbCrLf & "--- Compare types obtained by different methods:")

        Dim t As Type = GetType(Dictionary(Of String, Test))
        Console.WriteLine(vbTab & "Are the constructed types equal? " _
            & (t Is constructed))
        Console.WriteLine(vbTab & "Are the generic types equal? " _ 
            & (t.GetGenericTypeDefinition() Is 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 ({0}):", _
            typeArguments.Length)
        For Each tParam As Type In typeArguments       
            Console.WriteLine(vbTab & vbTab & tParam.ToString())
        Next
    End Sub
End Class

' This example produces the following output:
'
'--- Create a constructed type from the generic Dictionary type.
'
'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
'
'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
'
'--- Compare types obtained by different methods:
'        Are the constructed types equal? True
'        Are the generic types equal? True

備註

MakeGenericType方法可讓您撰寫程式碼,將特定類型指派給類型參數的泛型類型定義,因此建立Type代表特定的建構的類型的物件。The MakeGenericType method allows you to write code that assigns specific types to the type parameters of a generic type definition, thus creating a Type object that represents a particular constructed type. 您可以使用這個Type物件來建立建構類型的執行階段執行個體。You can use this Type object to create run-time instances of the constructed type.

類型建構MakeGenericType可以開啟,也就是某些其類型引數可以是封閉式泛型方法或類型的型別參數。Types constructed with MakeGenericType can be open, that is, some of their type arguments can be type parameters of enclosing generic methods or types. 當發出動態組件時,您可以使用這種開放式建構的類型。You might use such open constructed types when you emit dynamic assemblies. 例如,假設類別BaseDerived下列程式碼。For example, consider the classes Base and Derived in the following code.

generic<typename T, typename U>
    public ref class Base { };
generic<typename V>
    public ref class Derived : Base<int, V> { };
public class Base<T, U> { }
public class Derived<V> : Base<int, V> { }
Public Class Base(Of T, U)
End Class
Public Class Derived(Of V)
    Inherits Base(Of Integer, V)
End Class

若要產生Derived在動態組件,就必須建構其基底類型。To generate Derived in a dynamic assembly, it is necessary to construct its base type. 若要這樣做,請呼叫MakeGenericType方法Type物件,表示類別Base,使用泛型型別引數Int32型別參數VDerivedTo do this, call the MakeGenericType method on a Type object representing the class Base, using the generic type arguments Int32 and the type parameter V from Derived. 因為型別和泛型型別參數都表示所Type物件,包含這兩個陣列可以傳遞至MakeGenericType方法。Because types and generic type parameters are both represented by Type objects, an array containing both can be passed to the MakeGenericType method.

注意

建構的類型,例如Base<int, V>有用時,發出程式碼,但您不能呼叫MakeGenericType方法,這個型別上的因為它不是泛型類型定義。A constructed type such as Base<int, V> is useful when emitting code, but you cannot call the MakeGenericType method on this type because it is not a generic type definition. 若要建立封閉式的建構型別可以具現化,請先呼叫GetGenericTypeDefinition方法來取得Type物件,代表泛型類型定義,然後呼叫MakeGenericType使用所需的類型引數。To create a closed constructed type that can be instantiated, first call the GetGenericTypeDefinition method to get a Type object representing the generic type definition and then call MakeGenericType with the desired type arguments.

Type所傳回的物件MakeGenericType等同於Type藉由呼叫取得GetType產生的方法建構的型別,或GetType建構建立從相同泛型類型的任何的方法。使用相同的型別引數的型別定義。The Type object returned by MakeGenericType is the same as the Type obtained by calling the GetType method of the resulting constructed type, or the GetType method of any constructed type that was created from the same generic type definition using the same type arguments.

注意

泛型型別的陣列本身就不是泛型型別。An array of generic types is not itself a generic type. 您不能呼叫MakeGenericType陣列上輸入,例如C<T>[](Dim ac() As C(Of T) Visual Basic 中)。You cannot call MakeGenericType on an array type such as C<T>[] (Dim ac() As C(Of T) in Visual Basic). 若要建構的封閉式泛型型別,從C<T>[],呼叫GetElementType取得泛型型別定義C<T>; 呼叫MakeGenericType泛型型別定義,來建立建構的類型,最後呼叫MakeArrayType方法若要建立此陣列型別建構的型別。To construct a closed generic type from C<T>[], call GetElementType to obtain the generic type definition C<T>; call MakeGenericType on the generic type definition to create the constructed type; and finally call the MakeArrayType method on the constructed type to create the array type. 這也是指標類型,則為 true 並ref型別 (ByRef Visual Basic 中)。The same is true of pointer types and ref types (ByRef in Visual Basic).

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。For a list of the invariant conditions for terms used in generic reflection, see the IsGenericType property remarks.

巢狀類型Nested Types

如果泛型類型定義使用C#, C++,或 Visual Basic 中,則其巢狀的類型是所有泛型。If a generic type is defined using C#, C++, or Visual Basic, then its nested types are all generic. 這是 true,即使巢狀型別有自己的任何型別參數,因為所有的三種語言包含封入型別的型別參數清單中的巢狀型別的型別參數。This is true even if the nested types have no type parameters of their own, because all three languages include the type parameters of enclosing types in the type parameter lists of nested types. 請考慮下列類別:Consider the following classes:

generic<typename T> public ref class Outermost
{
public:
    generic<typename U> ref class Inner
    {
    public:
        generic<typename V> ref class Innermost1 {};
        ref class Innermost2 {};
    };
};
public class Outermost<T>
{
    public class Inner<U>
    {
        public class Innermost1<V> {}
        public class Innermost2 {}
    }
}
Public Class Outermost(Of T)
    Public Class Inner(Of U)
        Public Class Innermost1(Of V)
        End Class
        Public Class Innermost2
        End Class
    End Class
End Class

巢狀類別的型別參數清單Inner有兩個類型參數,TU,其中第一個是其封入類別的型別參數。The type parameter list of the nested class Inner has two type parameters, T and U, the first of which is the type parameter of its enclosing class. 同樣地,巢狀類別的型別參數清單Innermost1有三個類型參數, TU,以及V,使用TU來自其封入類別。Similarly, the type parameter list of the nested class Innermost1 has three type parameters, T, U, and V, with T and U coming from its enclosing classes. 巢狀的類別Innermost2有兩個類型參數,TU,這是來自其封入類別。The nested class Innermost2 has two type parameters, T and U, which come from its enclosing classes.

如果封入類型的參數清單會有一個以上的型別參數,在順序中的所有型別參數會包含巢狀類型的類型參數清單中。If the parameter list of the enclosing type has more than one type parameter, all the type parameters in order are included in the type parameter list of the nested type.

若要建構泛型型別從巢狀類型的泛型類型定義,請呼叫MakeGenericType串連起來型別引數陣列的所有封入類型、 最外層的泛型型別,開頭和結尾所構成的陣列的方法型別引數陣列的巢狀型別本身,如果它有自己的型別參數。To construct a generic type from the generic type definition for a nested type, call the MakeGenericType method with the array formed by concatenating the type argument arrays of all the enclosing types, beginning with the outermost generic type, and ending with the type argument array of the nested type itself, if it has type parameters of its own. 若要建立的執行個體Innermost1,呼叫MakeGenericType與陣列,包含要指派給 T、 U 和 V 的三種類型的方法。若要建立的執行個體Innermost2,呼叫MakeGenericType方法與陣列,包含兩種類型,以指派給 T 和 u。To create an instance of Innermost1, call the MakeGenericType method with an array containing three types, to be assigned to T, U, and V. To create an instance of Innermost2, call the MakeGenericType method with an array containing two types, to be assigned to T and U.

語言傳播型別參數,以這種方式中封入類型,因此您可以使用封入類型的型別參數,以定義巢狀類型的欄位。The languages propagate the type parameters of enclosing types in this fashion so you can use the type parameters of an enclosing type to define fields of nested types. 否則,型別參數不是在範圍內的巢狀類型的主體內。Otherwise, the type parameters would not be in scope within the bodies of the nested types. 您可定義巢狀的類型,而不會傳播的封入類型,透過發出動態組件中的程式碼或使用的型別參數Ilasm.exe (IL Assembler)It is possible to define nested types without propagating the type parameters of enclosing types, by emitting code in dynamic assemblies or by using the Ilasm.exe (IL Assembler). MSIL 組譯工具,請考慮下列程式碼:Consider the following code for the MSIL assembler:

.class public Outer<T> {  
    .class nested public Inner<U> {  
        .class nested public Innermost {  
        }  
    }  
}  

在此範例中,它不是可以定義類型的欄位T或是U類別中Innermost,因為這些型別參數不在範圍內。In this example, it is not possible to define a field of type T or U in class Innermost, because those type parameters are not in scope. 下列的組合器程式碼定義,其行為的方式就好似中定義的巢狀的類別C++,Visual Basic 和C#:The following assembler code defines nested classes that behave the way they would if defined in C++, Visual Basic, and C#:

.class public Outer<T> {  
    .class nested public Inner<T, U> {  
        .class nested public Innermost<T, U, V> {  
        }  
    }  
}  

您可以使用Ildasm.exe (IL 反組譯工具)檢查高階語言中定義的巢狀的類別,並觀察這個命名配置。You can use the Ildasm.exe (IL Disassembler) to examine nested classes defined in the high-level languages and observe this naming scheme.

適用於

另請參閱