Type.GenericParameterPosition Propiedad

Definición

Obtiene la posición del parámetro de tipo en la lista de parámetros de tipo del tipo o método genérico que declaró el parámetro, siempre que el objeto Type represente un parámetro de tipo de un tipo genérico o de un 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:
 abstract property int GenericParameterPosition { int get(); };
public:
 virtual property int GenericParameterPosition { int get(); };
public abstract int GenericParameterPosition { get; }
public virtual int GenericParameterPosition { get; }
member this.GenericParameterPosition : int
Public MustOverride ReadOnly Property GenericParameterPosition As Integer
Public Overridable ReadOnly Property GenericParameterPosition As Integer

Valor de propiedad

Int32

Posición de un parámetro de tipo en la lista de parámetros de tipo del método o tipo genérico que define el parámetro.The position of a type parameter in the type parameter list of the generic type or method that defines the parameter. Los números de posición comienzan en 0.Position numbers begin at 0.

Excepciones

El tipo actual no representa un parámetro de tipo.The current type does not represent a type parameter. Es decir, IsGenericParameter devuelve false.That is, IsGenericParameter returns false.

Ejemplos

En el ejemplo siguiente se define una clase genérica con dos parámetros de tipo y se define una segunda clase genérica que se deriva de la primera clase.The following example defines a generic class with two type parameters and defines a second generic class that derives from the first class. La clase base de la clase derivada tiene dos argumentos de tipo: el primero es Int32 y el segundo es un parámetro de tipo del 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. En el ejemplo se muestra información sobre estas clases genéricas, incluidas las posiciones indicadas por la GenericParameterPosition propiedad.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

' 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)
' 

Comentarios

La GenericParameterPosition propiedad devuelve la posición de un parámetro de tipo en la lista de parámetros de la definición de tipo genérico o la definición de método genérico donde se definió originalmente el parámetro de tipo.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. Las DeclaringType DeclaringMethod propiedades y identifican la definición de tipo o método genérico:The DeclaringType and DeclaringMethod properties identify the generic type or method definition:

  • Si la DeclaringMethod propiedad devuelve MethodInfo , que MethodInfo representa una definición de método genérico y el objeto actual Type representa un parámetro de tipo de esa definición 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.

  • Si la DeclaringMethod propiedad devuelve null , la DeclaringType propiedad siempre devuelve un Type objeto que representa una definición de tipo genérico y el Type objeto actual representa un parámetro de tipo de esa definición de tipo genérico.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 proporcionar el contexto correcto para el valor de la GenericParameterPosition propiedad, es necesario identificar el tipo o método genérico al que pertenece un parámetro de tipo.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 ejemplo, considere el valor devuelto del método genérico GetSomething en el código siguiente: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

El tipo devuelto por GetSomething depende de los argumentos de tipo proporcionados a la clase A y a GetSomething sí mismo.The type returned by GetSomething depends on the type arguments supplied to class A and to GetSomething itself. Puede obtener un MethodInfo para GetSomething y desde el que puede obtener el tipo de valor devuelto.You can obtain a MethodInfo for GetSomething, and from that you can obtain the return type. Al examinar los parámetros de tipo del tipo de valor devuelto, GenericParameterPosition devuelve 0 para ambos.When you examine the type parameters of the return type, GenericParameterPosition returns 0 for both. La posición de V es 0 porque V es el primer parámetro de tipo de la lista de parámetros de tipo para la clase A .The position of V is 0 because V is the first type parameter in the type parameter list for class A. La posición de X es 0 porque X es el primer parámetro de tipo de la lista de parámetros de tipo de GetSomething .The position of X is 0 because X is the first type parameter in the type parameter list for GetSomething.

Nota

Si se llama a la GenericParameterPosition propiedad, se produce una excepción si el actual Type no representa un parámetro de tipo.Calling the GenericParameterPosition property causes an exception if the current Type does not represent a type parameter. Cuando examine los argumentos de tipo de un tipo construido abierto, utilice la IsGenericParameter propiedad para indicar cuáles son los parámetros de tipo y cuáles son 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. La IsGenericParameter propiedad devuelve true para un parámetro de tipo; a continuación, puede utilizar el GenericParameterPosition método para obtener su posición y usar las DeclaringMethod DeclaringType propiedades y para determinar el método genérico o la definición de tipo que la 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.

Se aplica a

Consulte también