Type.GenericParameterPosition Type.GenericParameterPosition Type.GenericParameterPosition Type.GenericParameterPosition Property

Definição

Obtém a posição do parâmetro de tipo, na lista de parâmetros de tipo, do tipo genérico ou do método que declarou o parâmetro, quando o objeto Type representa um parâmetro de tipo de um tipo genérico ou método genérico.Gets the position of the type parameter in the type parameter list of the generic type or method that declared the parameter, when the Type object represents a type parameter of a generic type or a generic method.

public:
 virtual property int GenericParameterPosition { int get(); };
public virtual int GenericParameterPosition { get; }
member this.GenericParameterPosition : int
Public Overridable ReadOnly Property GenericParameterPosition As Integer

Valor da propriedade

A posição de um parâmetro de tipo na lista de parâmetros de tipo do tipo ou método genérico que define o parâmetro.The position of a type parameter in the type parameter list of the generic type or method that defines the parameter. Os números de posição começam em 0.Position numbers begin at 0.

Exceções

O tipo atual não representa um parâmetro de tipo.The current type does not represent a type parameter. Ou seja, IsGenericParameter retorna false.That is, IsGenericParameter returns false.

Exemplos

O exemplo a seguir define uma classe genérica com dois parâmetros de tipo e define uma segunda classe genérica que deriva da primeira classe.The following example defines a generic class with two type parameters and defines a second generic class that derives from the first class. A classe base da classe derivada tem dois argumentos de tipo: o primeiro Int32é, e o segundo é um parâmetro de tipo do tipo derivado.The derived class's base class has two type arguments: the first is Int32, and the second is a type parameter of the derived type. O exemplo exibe informações sobre essas classes genéricas, incluindo as posições relatadas GenericParameterPosition pela propriedade.The example displays information about these generic classes, including the positions reported by the GenericParameterPosition property.

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

// Define a base class with two type parameters.
generic< class T,class U >
public ref class Base {};

// Define a derived class. The derived class inherits from a constructed
// class that meets the following criteria:
//   (1) Its generic type definition is Base<T, U>.
//   (2) It specifies int for the first type parameter.
//   (3) For the second type parameter, it uses the same type that is used
//       for the type parameter of the derived class.
// Thus, the derived class is a generic type with one type parameter, but
// its base class is an open constructed type with one type argument and
// one type parameter.
generic<class V>
public ref class Derived : Base<int,V> {};

public ref class Test
{
public:
    static void Main()
    {
        Console::WriteLine( 
            L"\r\n--- Display a generic type and the open constructed");
        Console::WriteLine(L"    type from which it is derived.");
      
        // Create a Type object representing the generic type definition
        // for the Derived type. Note the absence of type arguments.
        //
        Type^ derivedType = Derived::typeid;
        DisplayGenericTypeInfo(derivedType);
      
        // Display its open constructed base type.
        DisplayGenericTypeInfo(derivedType->BaseType);
    }


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);
        Console::WriteLine(L"\tDoes it have unassigned generic parameters? {0}",
            t->ContainsGenericParameters);
        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);
            
                // IsGenericParameter is true only for generic type
                // parameters.
                //
                if (tParam->IsGenericParameter)
                {
                    Console::WriteLine( 
                        L"\t\t{0}  (unassigned - parameter position {1})", 
                        tParam, tParam->GenericParameterPosition);
                }
                else
                {
                    Console::WriteLine(L"\t\t{0}", tParam);
                }
            }
        }
    }
};

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

/* This example produces the following output:

--- Display a generic type and the open constructed
    type from which it is derived.

Derived`1[V]
        Is this a generic type definition? True
        Is it a generic type? True
        Does it have unassigned generic parameters? True
        List type arguments (1):
                V  (unassigned - parameter position 0)

Base`2[System.Int32,V]
        Is this a generic type definition? False
        Is it a generic type? True
        Does it have unassigned generic parameters? True
        List type arguments (2):
                System.Int32
                V  (unassigned - parameter position 0)
 */
using System;
using System.Reflection;
using System.Collections.Generic;

// Define a base class with two type parameters.
public class Base<T, U> { }

// Define a derived class. The derived class inherits from a constructed
// class that meets the following criteria:
//   (1) Its generic type definition is Base<T, U>.
//   (2) It specifies int for the first type parameter.
//   (3) For the second type parameter, it uses the same type that is used
//       for the type parameter of the derived class.
// Thus, the derived class is a generic type with one type parameter, but
// its base class is an open constructed type with one type argument and
// one type parameter.
public class Derived<V> : Base<int, V> { }

public class Test
{
    public static void Main()
    {
        Console.WriteLine(
            "\r\n--- Display a generic type and the open constructed");
        Console.WriteLine("    type from which it is derived.");

        // Create a Type object representing the generic type definition 
        // for the Derived type, by omitting the type argument. (For
        // types with multiple type parameters, supply the commas but
        // omit the type arguments.) 
        //
        Type derivedType = typeof(Derived<>);
        DisplayGenericTypeInfo(derivedType);

        // Display its open constructed base type.
        DisplayGenericTypeInfo(derivedType.BaseType);
    }

    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);

        Console.WriteLine("\tDoes it have unassigned generic parameters? {0}", 
            t.ContainsGenericParameters);

        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)
            {
                // IsGenericParameter is true only for generic type
                // parameters.
                //
                if (tParam.IsGenericParameter)
                {
                    Console.WriteLine(
                        "\t\t{0}  (unassigned - parameter position {1})",
                        tParam,
                        tParam.GenericParameterPosition);
                }
                else
                {
                    Console.WriteLine("\t\t{0}", tParam);
                }
            }
        }
    }
}

/* This example produces the following output:

--- Display a generic type and the open constructed
    type from which it is derived.

Derived`1[V]
        Is this a generic type definition? True
        Is it a generic type? True
        Does it have unassigned generic parameters? True
        List type arguments (1):
                V  (unassigned - parameter position 0)

Base`2[System.Int32,V]
        Is this a generic type definition? False
        Is it a generic type? True
        Does it have unassigned generic parameters? True
        List type arguments (2):
                System.Int32
                V  (unassigned - parameter position 0)
 */
Imports System.Reflection
Imports System.Collections.Generic

' Define a base class with two type parameters.
Public Class Base(Of T, U)
End Class

' Define a derived class. The derived class inherits from a constructed
' class that meets the following criteria:
'   (1) Its generic type definition is Base<T, U>.
'   (2) It uses int for the first type parameter.
'   (3) For the second type parameter, it uses the same type that is used
'       for the type parameter of the derived class.
' Thus, the derived class is a generic type with one type parameter, but
' its base class is an open constructed type with one assigned type
' parameter and one unassigned type parameter.
Public Class Derived(Of V)
    Inherits Base(Of Integer, V)
End Class

Public Class Test
    
    Public Shared Sub Main() 
        Console.WriteLine(vbCrLf _
            & "--- Display a generic type and the open constructed")
        Console.WriteLine("    type from which it is derived.")
        
        ' Create a Type object representing the generic type definition 
        ' for the Derived type, by omitting the type argument. (For
        ' types with multiple type parameters, supply the commas but
        ' omit the type arguments.) 
        '
        Dim derivedType As Type = GetType(Derived(Of ))
        DisplayGenericTypeInfo(derivedType)
        
        ' Display its open constructed base type.
        DisplayGenericTypeInfo(derivedType.BaseType)
    
    End Sub
    
    Private Shared Sub DisplayGenericTypeInfo(ByVal t As Type) 
        Console.WriteLine(vbCrLf & "{0}", t)
        
        Console.WriteLine(vbTab & "Is this a generic type definition? " _
            & t.IsGenericTypeDefinition)
        
        Console.WriteLine(vbTab & "Is it a generic type? " _
            & t.IsGenericType)
        
        Console.WriteLine(vbTab _
            & "Does it have unassigned generic parameters? " _
            & t.ContainsGenericParameters)
        
        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
                ' IsGenericParameter is true only for generic type
                ' parameters.
                '
                If tParam.IsGenericParameter Then
                    Console.WriteLine(vbTab & vbTab & tParam.ToString() _
                        & "  (unassigned - parameter position " _
                        & tParam.GenericParameterPosition & ")")
                Else
                    Console.WriteLine(vbTab & vbTab & tParam.ToString())
                End If
            Next tParam
        End If
    
    End Sub
End Class 'Test

' This example produces the following output:
'
'--- Display a generic type and the open constructed
'    type from which it is derived.
'
'Derived`1[V]
'        Is this a generic type definition? True
'        Is it a generic type? True
'        Does it have unassigned generic parameters? True
'        List type arguments (1):
'                V  (unassigned - parameter position 0)
'
'Base`2[System.Int32,V]
'        Is this a generic type definition? False
'        Is it a generic type? True
'        Does it have unassigned generic parameters? True
'        List type parameters (2):
'                System.Int32
'                V  (unassigned - parameter position 0)
' 

Comentários

A GenericParameterPosition propriedade retorna a posição de um parâmetro de tipo na lista de parâmetros da definição de tipo genérico ou definição de método genérico em que o parâmetro de tipo foi originalmente definido.The GenericParameterPosition property returns the position of a type parameter in the parameter list of the generic type definition or generic method definition where the type parameter was originally defined. As DeclaringType propriedades DeclaringMethod e identificam o tipo genérico ou a definição do método:The DeclaringType and DeclaringMethod properties identify the generic type or method definition:

  • Se a DeclaringMethod Propriedade retornar um MethodInfo, que MethodInfo representa uma definição de método genérico, e o Type objeto atual representar um parâmetro de tipo dessa definição de método genérico.If the DeclaringMethod property returns a MethodInfo, that MethodInfo represents a generic method definition, and the current Type object represents a type parameter of that generic method definition.

  • Se a DeclaringMethod Propriedade retornar null, a DeclaringType propriedade sempre retorna um Type objeto que representa uma definição de tipo genérico e o objeto Type atual representa um parâmetro de tipo desse tipo genérico defini.If the DeclaringMethod property returns null, then the DeclaringType property always returns a Type object representing a generic type definition, and the current Type object represents a type parameter of that generic type definition.

Para fornecer o contexto correto para o valor da GenericParameterPosition Propriedade, é necessário identificar o tipo genérico ou o método ao qual um parâmetro de tipo pertence.To provide the correct context for the value of the GenericParameterPosition property, it is necessary to identify the generic type or method a type parameter belongs to. Por exemplo, considere o valor de retorno do método GetSomething genérico no código a seguir:For example, consider the return value of the generic method GetSomething in the following code:

generic<typename T, typename U> public ref class B { };
generic<typename V> public ref class A
{
public:
    generic<typename X> B<V, X>^ GetSomething()
    {
        return gcnew B<V, X>();
    }
};
public class B<T, U> { }
public class A<V>
{
    public B<V, X> GetSomething<X>()
    {
        return new B<V, X>();
    }
}
Public Class B(Of T, U)
End Class
Public Class A(Of V)
    Public Function GetSomething(Of X)() As B(Of V, X)
        Return New B(Of V, X)()
    End Function
End Class

O tipo retornado por GetSomething depende dos argumentos de tipo fornecidos à classe A e a GetSomething si mesmo.The type returned by GetSomething depends on the type arguments supplied to class A and to GetSomething itself. Você pode obter um MethodInfo para GetSomething, e de que você pode obter o tipo de retorno.You can obtain a MethodInfo for GetSomething, and from that you can obtain the return type. Quando você examina os parâmetros de tipo do tipo de retorno GenericParameterPosition , retorna 0 para ambos.When you examine the type parameters of the return type, GenericParameterPosition returns 0 for both. A posição de V é 0 porque V é o primeiro parâmetro de tipo na lista de parâmetros de tipo Ada classe.The position of V is 0 because V is the first type parameter in the type parameter list for class A. A posição de X é 0 porque X é o primeiro parâmetro de tipo na lista de parâmetros de GetSomethingtipo para.The position of X is 0 because X is the first type parameter in the type parameter list for GetSomething.

Observação

Chamar a GenericParameterPosition Propriedade causará uma exceção se Type a atual não representar um parâmetro de tipo.Calling the GenericParameterPosition property causes an exception if the current Type does not represent a type parameter. Quando você examina os argumentos de tipo de um tipo construído aberto, use IsGenericParameter a propriedade para informar quais são os parâmetros de tipo e quais são os tipos.When you examine the type arguments of an open constructed type, use the IsGenericParameter property to tell which are type parameters and which are types. A IsGenericParameter propriedade retorna true para um parâmetro de tipo; você pode usar o GenericParameterPosition método para obter sua posição e usar as DeclaringMethod propriedades DeclaringType e para determinar o método genérico ou a definição de tipo que a define .The IsGenericParameter property returns true for a type parameter; you can then use the GenericParameterPosition method to obtain its position and use the DeclaringMethod and DeclaringType properties to determine the generic method or type definition that defines it.

Aplica-se a

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