Type.MakeGenericType(Type[]) Metoda

Definice

Obor názvů:

System

Sestavení:

netstandard.dll, System.Runtime.dll

Zdroj:

Type.cs

Nahradí prvky pole typů parametry typu aktuální definice obecného typu a vrátí Type objekt představující výsledný vytvořený typ.

public:
 virtual Type ^ MakeGenericType(... cli::array <Type ^> ^ typeArguments);

[System.Diagnostics.CodeAnalysis.RequiresDynamicCode("The native code for this instantiation might not be available at runtime.")]
[System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("If some of the generic arguments are annotated (either with DynamicallyAccessedMembersAttribute, or generic constraints), trimming can't validate that the requirements of those annotations are met.")]
public virtual Type MakeGenericType(params Type[] typeArguments);

[<System.Diagnostics.CodeAnalysis.RequiresDynamicCode("The native code for this instantiation might not be available at runtime.")>]
[<System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("If some of the generic arguments are annotated (either with DynamicallyAccessedMembersAttribute, or generic constraints), trimming can't validate that the requirements of those annotations are met.")>]
abstract member MakeGenericType : Type[] -> Type
override this.MakeGenericType : Type[] -> Type

Public Overridable Function MakeGenericType (ParamArray typeArguments As Type()) As Type

Parametry

typeArguments

Type[]

Pole typů, které se mají nahradit parametry typu aktuálního obecného typu.

Návraty

Type

A Type představující konstruovaný typ vytvořený nahrazením prvků typeArguments parametrů typu aktuálního obecného typu.

Atributy

RequiresDynamicCodeAttribute RequiresUnreferencedCodeAttribute

Výjimky

InvalidOperationException

Aktuální typ nepředstavuje definici obecného typu. To znamená, IsGenericTypeDefinition že vrátí false.

ArgumentNullException

typeArguments je null.

nebo

Jakýkoli prvek typeArguments je null.

ArgumentException

Počet prvků není typeArguments stejný jako počet parametrů typu v aktuální definici obecného typu.

nebo

Jakýkoli prvek typeArguments nevyhovuje omezením zadaným pro odpovídající parametr typu aktuálního obecného typu.

nebo

typeArguments obsahuje prvek, který je typem ukazatele (IsPointer vrátí true), typ by-ref (IsByRef vrátí true) nebo Void.

NotSupportedException

Vyvolaná metoda není podporována v základní třídě. Odvozené třídy musí poskytovat implementaci.

Příklady

Následující příklad používá metodu MakeGenericType k vytvoření vytvořeného typu z definice obecného typu pro Dictionary<TKey,TValue> typ. Vytvořený typ představuje Dictionary<TKey,TValue>Test objekty s řetězcovými klíči.

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
 */

open System
open System.Collections.Generic

type Test() = class end

let displayTypeInfo (t: Type) =
    printfn $"\r\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 "\r\n--- Create a constructed type from the generic Dictionary type."

// Create a type object representing the generic Dictionary 
// type, by calling .GetGenericTypeDefinition().
let generic = typeof<Dictionary<_,_>>.GetGenericTypeDefinition()
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.
let typeArgs = [| typeof<string>; typeof<Test> |]

// Create a Type object representing the constructed generic type.
let constructed = generic.MakeGenericType typeArgs
displayTypeInfo constructed

(* 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
 *)

Imports System.Reflection
Imports System.Collections.Generic

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

Poznámky

Další informace o tomto rozhraní API naleznete v tématu Doplňkové poznámky k rozhraní API pro Type.MakeGenericType.

Viz také

• IsGenericTypeDefinition
• GetGenericTypeDefinition()
• Reflexe a generické typy
• Postupy: Zkoumání a vytváření instancí obecných typů pomocí reflexe