TypeFilter 委托

定义

命名空间:

System.Reflection

程序集:

System.Runtime.dll

程序集:

System.Reflection.dll

程序集:

mscorlib.dll

程序集:

netstandard.dll

筛选 Type 对象数组中表示的类。

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 

参数

m

Type

对其应用筛选器的 Type 对象。

filterCriteria

Object

用于筛选列表的任意对象。

返回值

Boolean

若要在筛选后的列表中包括 Type，则为 true；否则为 false。

属性

SerializableAttribute ComVisibleAttribute

示例

此示例演示如何定义与委托原型匹配 TypeFilter 的方法，以便使用反射来筛选或返回匹配项的子集。

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

注解

委托 TypeFilter 用于筛选类列表。 具体而言，可以使用它筛选对象数组中表示的 Type 类。 该方法 Type.FindInterfaces 使用此委托筛选其返回的接口列表。 每个派生类 Delegate 都有 MulticastDelegate 一个构造函数和一个 DynamicInvoke 方法。 请参阅说明 Delegate中给出的 Visual C++ 代码示例。

扩展方法

GetMethodInfo(Delegate)

获取指示指定委托表示的方法的对象。

另请参阅

• FindInterfaces(TypeFilter, Object)
• Object
• Delegate
• MulticastDelegate