TypeFilter 委托

筛选在 Type 对象数组中表示的类。

**命名空间:**System.Reflection
**程序集:**mscorlib（在 mscorlib.dll 中）

语法

声明
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Delegate Function TypeFilter ( _
    m As Type, _
    filterCriteria As Object _
) As Boolean
用法
Dim instance As New TypeFilter(AddressOf HandlerMethod)

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public delegate bool TypeFilter (
    Type m,
    Object filterCriteria
)

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public delegate bool TypeFilter (
    Type^ m, 
    Object^ filterCriteria
)

/** @delegate */
/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public delegate boolean TypeFilter (
    Type m, 
    Object filterCriteria
)

JScript 支持使用委托，但不支持进行新的声明。

参数

• m
  筛选器应用到的 Type 对象。

• filterCriteria
  用于筛选列表的任意对象。

返回值

如果包括已筛选列表中的 Type，则为 true；否则为 false。

备注

TypeFilter 委托用于筛选类列表。具体说来就是使用该委托筛选在 Type 对象数组中表示的类。Type.FindInterfaces 方法使用该委托筛选它返回的接口列表。Delegate 和 MulticastDelegate 的每个派生类都具有一个构造函数和一个 DynamicInvoke 方法。请参见 Delegate 说明中给出的 C++ 托管扩展代码示例。

示例

此示例显示如何定义与 TypeFilter 委托原型匹配的方法，该方法允许使用反射筛选或返回匹配项的子集。

Imports system
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 four interfaces; two are defined in this assembly and two are defined in another assembly.
Public Class MyRetailer
    Implements IBookRetailer, IMusicRetailer, IComparable, ICloneable

    ' For demonstration purposes, this method returns nothing; it just allows the code to compile.
    Public Function Clone() As Object Implements System.ICloneable.Clone
        Return Nothing
    End Function

    ' For demonstration purposes, this method returns nothing; it just allows the code to compile.
    Public Function CompareTo(ByVal obj As Object) As Integer Implements System.IComparable.CompareTo
        Return Nothing
    End Function

    ' For demonstration purposes, this method returns nothing; it just allows the code to compile.
    Public Sub ApplyDiscout() Implements IBookRetailer.ApplyDiscount
    End Sub

    ' For demonstration purposes, this method returns nothing; it just allows the code to compile.
    Public Sub Purchase() Implements IBookRetailer.Purchase
    End Sub

    ' For demonstration purposes, this method returns nothing; it just allows the code to compile.
    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 interfaces() As Type = _
            GetType(MyRetailer).FindInterfaces(AddressOf TypeFilter, Assembly.GetExecutingAssembly().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):")
        Dim t As Type
        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 interface defined.
    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

' Output will vary based on the contents of the C drive.
'
' This code produces the following output.
' MyRetailer implements the following interfaces (defined in this assembly):
'   IBookRetailer
'   IMusicRetailer

平台

Windows 98、Windows 2000 SP4、Windows Millennium Edition、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。

版本信息

.NET Framework

受以下版本支持：2.0、1.1、1.0

请参见

参考

System.Reflection 命名空间
FindInterfaces
Object
Delegate
MulticastDelegate