TypeFilter Delegát

  • Reference

Definice

Obor názvů:
System.Reflection
Sestavení:
System.Runtime.dll
Sestavení:
System.Reflection.dll
Sestavení:
mscorlib.dll
Sestavení:
netstandard.dll

Filtruje třídy reprezentované v poli Type objektů.

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

Parametry

m
Type

Objekt Type , na který se filtr použije.

filterCriteria
Object

Libovolný objekt použitý k filtrování seznamu.

Návratová hodnota

Boolean

true zahrnout do Type filtrovaného seznamu; jinak false.

Atributy
SerializableAttribute ComVisibleAttribute

Příklady

Tento příklad ukazuje, jak definovat metodu odpovídající prototypu TypeFilter delegáta, která umožňuje použít reflexi k filtrování nebo vrácení podmnožině odpovídajících položek.

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

Poznámky

Delegát TypeFilter slouží k filtrování seznamu tříd. Konkrétně ji použijete k filtrování tříd reprezentovaných v poli Type objektů. Tato Type.FindInterfaces metoda používá tohoto delegáta k filtrování seznamu rozhraní, která vrací. Každá odvozená třída Delegate a MulticastDelegate má konstruktor a metodu DynamicInvoke . Podívejte se na příklad kódu visual C++ uvedený v popisu .Delegate

Metody rozšíření

GetMethodInfo(Delegate)

Získá objekt, který představuje metodu reprezentovanou zadaným delegátem.

Platí pro

Viz také