TypeFilter Delegar
Definição
Importante
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Filtra as classes representadas em uma matriz de objetos Type.
public delegate bool TypeFilter(Type ^ m, System::Object ^ filterCriteria);
public delegate bool TypeFilter(Type m, object? filterCriteria);
public delegate bool TypeFilter(Type m, object filterCriteria);
[System.Serializable]
public delegate bool TypeFilter(Type m, object filterCriteria);
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public delegate bool TypeFilter(Type m, object filterCriteria);
type TypeFilter = delegate of Type * obj -> bool
[<System.Serializable>]
type TypeFilter = delegate of Type * obj -> bool
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type TypeFilter = delegate of Type * obj -> bool
Public Delegate Function TypeFilter(m As Type, filterCriteria As Object) As Boolean
Parâmetros
- m
- Type
O objeto Type
ao qual o filtro é aplicado.
- filterCriteria
- Object
Um objeto arbitrário usado para filtrar a lista.
Valor Retornado
true
para incluir o Type na lista filtrada; caso contrário, false
.
- Atributos
Exemplos
Este exemplo mostra como definir um método que corresponda ao TypeFilter protótipo delegado, permitindo que você use reflexão para filtrar ou retornar um subconjunto de entradas correspondentes.
Imports System.Reflection
' This interface is defined in this assembly.
Public Interface IBookRetailer
Sub Purchase()
Sub ApplyDiscount()
End Interface
' This interface is also defined in this assembly.
Public Interface IMusicRetailer
Sub Purchase()
End Interface
' This class implements three interfaces;
' Two are defined in this assembly.
' One is defined in another assembly.
Public Class MyRetailer
Implements IBookRetailer, IMusicRetailer, IComparable
' For demonstration purposes, this method returns nothing.
Public Function CompareTo(ByVal obj As Object) As Integer Implements System.IComparable.CompareTo
Return Nothing
End Function
' For demonstration purposes only, this method does nothing.
Public Sub ApplyDiscount() Implements IBookRetailer.ApplyDiscount
End Sub
' For demonstration purposes only, this method does nothing.
Public Sub Purchase() Implements IBookRetailer.Purchase
End Sub
' For demonstration purposes only, this method does nothing.
Public Sub Purchase1() Implements IMusicRetailer.Purchase
End Sub
End Class
Module Module1
Sub Main()
' Find the interfaces defined by the MyRetailer class. Each interface found is passed to
' the TypeFilter method which checks if the interface is defined in the executing assembly.
Dim retailerType As Type = GetType(MyRetailer)
Dim interfaces() As Type = _
retailerType.FindInterfaces(AddressOf TypeFilter, retailerType.Assembly.GetName().ToString())
' Show the interfaces that are defined in this assembly that are also implemented by MyRetailer.
Console.WriteLine("MyRetailer implements the following interfaces (defined in this assembly):")
For Each t In interfaces
Console.WriteLine(" {0}", t.Name)
Next
End Sub
' This method is called by the FindInterfaces method.
' This method is called once per defined interface.
Function TypeFilter(ByVal t As Type, ByVal filterCriteria As Object) As Boolean
' Return true if interface is defined in the same
' assembly identified by the filterCriteria object.
Return t.Assembly.GetName().ToString() = CType(filterCriteria, String)
End Function
End Module
' The example displays the following output:
' MyRetailer implements the following interfaces (defined in this assembly):
' IBookRetailer
' IMusicRetailer
Comentários
O TypeFilter
delegado é usado para filtrar uma lista de classes. Especificamente, você o usa para filtrar as classes representadas em uma matriz de Type objetos. O Type.FindInterfaces método usa esse delegado para filtrar a lista de interfaces retornada. Cada classe derivada de Delegate e MulticastDelegate tem um construtor e um DynamicInvoke
método . Consulte o exemplo de código do Visual C++ dado na descrição de Delegate
.
Métodos de Extensão
GetMethodInfo(Delegate) |
Obtém um objeto que representa o método representado pelo delegado especificado. |