Attribute.IsDefined 方法

定義

命名空間:: System

組件:: netstandard.dll, System.Runtime.dll

組件:: System.Runtime.dll

組件:: mscorlib.dll

組件:: netstandard.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

判斷是否套用指定類型的自訂屬性於組合語言、模組、類型成員或方法參數。

多載

名稱	Description
IsDefined(ParameterInfo, Type, Boolean)	判斷是否將任何自定義屬性套用至方法參數。參數會指定要搜尋的方法參數、要搜尋的自定義屬性類型，以及是否要搜尋方法參數的上階。
IsDefined(Module, Type, Boolean)	判斷是否將任何自定義屬性套用至模組。參數會指定要搜尋的模組、要搜尋的自定義屬性類型，以及忽略的搜尋選項。
IsDefined(MemberInfo, Type, Boolean)	判斷是否將任何自定義屬性套用至型別的成員。參數會指定要搜尋的成員、要搜尋的自定義屬性類型，以及是否要搜尋成員的上階。
IsDefined(Assembly, Type, Boolean)	判斷是否將任何自定義屬性套用至元件。參數會指定要搜尋的元件、要搜尋的自定義屬性類型，以及忽略的搜尋選項。
IsDefined(MemberInfo, Type)	判斷是否將任何自定義屬性套用至型別的成員。參數會指定要搜尋的成員，以及要搜尋的自定義屬性類型。
IsDefined(Module, Type)	判斷指定型別的任何自定義屬性是否套用至模組。參數會指定要搜尋的模組，以及自定義屬性的類型。
IsDefined(Assembly, Type)	判斷是否將任何自定義屬性套用至元件。參數會指定要搜尋的元件，以及自定義屬性的類型。
IsDefined(ParameterInfo, Type)	判斷是否將任何自定義屬性套用至方法參數。參數會指定要搜尋的方法參數，以及要搜尋的自定義屬性類型。

IsDefined(ParameterInfo, Type, Boolean)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷是否將任何自定義屬性套用至方法參數。參數會指定要搜尋的方法參數、要搜尋的自定義屬性類型，以及是否要搜尋方法參數的上階。

public:
 static bool IsDefined(System::Reflection::ParameterInfo ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.ParameterInfo element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.ParameterInfo * Type * bool -> bool

Public Shared Function IsDefined (element As ParameterInfo, attributeType As Type, inherit As Boolean) As Boolean

參數

element: ParameterInfo

一個從 ParameterInfo 類別衍生出來的物件，描述該類別成員的參數。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

inherit: Boolean

若 true，則指定同時搜尋的 element 祖先以尋找自訂屬性。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

ExecutionEngineException

element 不是方法、建構子或型別。

範例

以下程式碼範例說明了以 a ParameterInfo 作為參數的使用IsDefined方法。

using System;
using System.Reflection;

namespace IsDef5CS
{
    public class TestClass
    {
        // Assign a ParamArray attribute to the parameter using the keyword.
        public void Method1(params String[] args)
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // Get the ParameterInfo array for the method parameters.
            ParameterInfo[] pInfo = mInfo.GetParameters();
            if (pInfo != null)
            {
                // See if the ParamArray attribute is defined.
                bool isDef = Attribute.IsDefined(pInfo[0],
                                                 typeof(ParamArrayAttribute));
                // Display the result.
                Console.WriteLine("The ParamArray attribute {0} defined for " +
                                  "parameter {1} of method {2}.",
                                  isDef ? "is" : "is not",
                                  pInfo[0].Name,
                                  mInfo.Name);
            }
            else
                Console.WriteLine("The parameters information could " +
                            "not be retrieved for method {0}.", mInfo.Name);
        }
    }
}

/*
 * Output:
 * The ParamArray attribute is defined for parameter args of method Method1.
 */

open System;

type TestClass() =
    // Assign a ParamArray attribute to the parameter.
    member _.Method1([<ParamArray>] args: string[]) = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// Get the ParameterInfo array for the method parameters.
let pInfo = mInfo.GetParameters()

if pInfo <> null then
    // See if the ParamArray attribute is defined.
    let isDef = Attribute.IsDefined(pInfo[0], typeof<ParamArrayAttribute>)

    // Display the result.
    printfn $"""The ParamArray attribute {if isDef then "is" else "is not"} defined for parameter {pInfo[0].Name} of method {mInfo.Name}."""
else
    printfn $"The parameters information could not be retrieved for method {mInfo.Name}."

// Output:
//  The ParamArray attribute is defined for parameter args of method Method1.

Imports System.Reflection

Module DemoModule
    Public Class TestClass
        ' Assign a ParamArray attribute to the parameter using the keyword.
        Public Sub Method1(ByVal ParamArray args As String())
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' Get the ParameterInfo array for the method parameters.
        Dim pInfo() As ParameterInfo = mInfo.GetParameters()
        If Not pInfo(0) Is Nothing Then
            ' See if the ParamArray attribute is defined.
            Dim isDef As Boolean = Attribute.IsDefined(pInfo(0), _
                                   GetType(ParamArrayAttribute))
            Dim strDef As String
            If isDef = True Then
                strDef = "is"
            Else
                strDef = "is not"
            End If
            ' Display the result.
            Console.WriteLine("The ParamArray attribute {0} defined " & _
                              "for parameter {1} of method {2}.", _
                              strDef, pInfo(0).Name, mInfo.Name)
        Else
            Console.WriteLine("Could not retrieve parameter information " & _
                              "for method {0}.", mInfo.Name)
        End If
    End Sub
End Module

' Output:
' The ParamArray attribute is defined for parameter args of method Method1.

適用於

IsDefined(Module, Type, Boolean)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷是否將任何自定義屬性套用至模組。參數會指定要搜尋的模組、要搜尋的自定義屬性類型，以及忽略的搜尋選項。

public:
 static bool IsDefined(System::Reflection::Module ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.Module element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.Module * Type * bool -> bool

Public Shared Function IsDefined (element As Module, attributeType As Type, inherit As Boolean) As Boolean

參數

element: Module

一個由描述可攜式可執行檔案的 Module 類別衍生出來的物件。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

inherit: Boolean

此參數被忽略，且不影響此方法的運作。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

範例

以下程式碼範例說明了以 a Module 作為參數的使用IsDefined方法。

using System;
using System.Diagnostics;

// Add the Debuggable attribute to the module.
[module:Debuggable(true, false)]
namespace IsDef2CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // See if the Debuggable attribute is defined for this module.
            bool isDef = Attribute.IsDefined(clsType.Module,
                typeof(DebuggableAttribute));
            // Display the result.
            Console.WriteLine("The Debuggable attribute {0} " +
                "defined for Module {1}.",
                isDef ? "is" : "is not",
                clsType.Module.Name);
            // If the attribute is defined, display the JIT settings.
            if (isDef)
            {
                // Retrieve the attribute itself.
                DebuggableAttribute dbgAttr = (DebuggableAttribute)
                    Attribute.GetCustomAttribute(clsType.Module,
                    typeof(DebuggableAttribute));
                if (dbgAttr != null)
                {
                    Console.WriteLine("JITTrackingEnabled is {0}.",
                        dbgAttr.IsJITTrackingEnabled);
                    Console.WriteLine("JITOptimizerDisabled is {0}.",
                        dbgAttr.IsJITOptimizerDisabled);
                }
                else
                    Console.WriteLine("The Debuggable attribute " +
                        "could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Debuggable attribute is defined for Module IsDef2CS.exe.
 * JITTrackingEnabled is True.
 * JITOptimizerDisabled is False.
 */

open System
open System.Diagnostics

// Add the Debuggable attribute to the module.
[<``module``: Debuggable(true, false)>]
do ()
    
type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// See if the Debuggable attribute is defined for this module.
let isDef = Attribute.IsDefined(clsType.Module, typeof<DebuggableAttribute>)

// Display the result.
printfn $"""The Debuggable attribute {if isDef then "is" else "is not"} defined for Module {clsType.Module.Name}."""

// If the attribute is defined, display the JIT settings.
if isDef then
    // Retrieve the attribute itself.
    let dbgAttr =
        Attribute.GetCustomAttribute(clsType.Module, typeof<DebuggableAttribute>)
        :?> DebuggableAttribute

    if dbgAttr <> null then
        printfn $"JITTrackingEnabled is {dbgAttr.IsJITTrackingEnabled}."
        printfn $"JITOptimizerDisabled is {dbgAttr.IsJITOptimizerDisabled}."            
    else
        printfn "The Debuggable attribute could not be retrieved."

// Output:
//  The Debuggable attribute is defined for Module IsDef2CS.exe.
//  JITTrackingEnabled is True.
//  JITOptimizerDisabled is False.

Imports System.Reflection
Imports System.Diagnostics

' Add the Debuggable attribute to the module.
<Module: Debuggable(True, False)> 

Module DemoModule
    Sub Main()
        ' Get the module type information to access its metadata.
        Dim modType As Type = GetType(DemoModule)
        ' See if the Debuggable attribute is defined.
        Dim isDef As Boolean = Attribute.IsDefined(modType.Module, _
                               GetType(DebuggableAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the result
        Console.WriteLine("The debuggable attribute {0} defined for " & _
                          "module {1}.", strDef, modType.Name)
        ' If the attribute is defined, display the JIT settings.
        If isDef = True Then
            ' Retrieve the attribute itself.
            Dim attr As Attribute = _
                Attribute.GetCustomAttribute(modType.Module, _
                GetType(DebuggableAttribute))
            If Not attr Is Nothing And TypeOf attr Is DebuggableAttribute Then
                Dim dbgAttr As DebuggableAttribute = _
                    CType(attr, DebuggableAttribute)
                Console.WriteLine("JITTrackingEnabled is {0}.", _
                    dbgAttr.IsJITTrackingEnabled.ToString())
                Console.WriteLine("JITOptimizerDisabled is {0}.", _
                    dbgAttr.IsJITOptimizerDisabled.ToString())
            Else
                Console.WriteLine("The Debuggable attribute could " & _
                                  "not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The debuggable attribute is defined for module DemoModule.
' JITTrackingEnabled is True.
' JITOptimizerDisabled is False.

備註

此方法忽略參數 inherit ，且不會搜尋的 element 祖先以尋找自訂屬性。

適用於

IsDefined(MemberInfo, Type, Boolean)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷是否將任何自定義屬性套用至型別的成員。參數會指定要搜尋的成員、要搜尋的自定義屬性類型，以及是否要搜尋成員的上階。

public:
 static bool IsDefined(System::Reflection::MemberInfo ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.MemberInfo element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.MemberInfo * Type * bool -> bool

Public Shared Function IsDefined (element As MemberInfo, attributeType As Type, inherit As Boolean) As Boolean

參數

element: MemberInfo

一個從 MemberInfo 類別衍生出來的物件，描述類別中的建構子、事件、欄位、方法、型別或屬性成員。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

inherit: Boolean

若 true，則指定同時搜尋的 element 祖先以尋找自訂屬性。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

NotSupportedException

element 不是建構子、方法、屬性、事件、類型或欄位。

範例

以下程式碼範例說明了以 a MemberInfo 作為參數的使用IsDefined方法。

using System;
using System.Reflection;

namespace IsDef4CS
{
    public class TestClass
    {
        // Assign the Obsolete attribute to a method.
        [Obsolete("This method is obsolete. Use Method2 instead.")]
        public void Method1()
        {}
        public void Method2()
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // See if the Obsolete attribute is defined for this method.
            bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
            // Display the result.
            Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
                isDef ? "is" : "is not", mInfo.Name, clsType.Name);
            // If it's defined, display the attribute's message.
            if (isDef)
            {
                ObsoleteAttribute obsAttr =
                                 (ObsoleteAttribute)Attribute.GetCustomAttribute(
                                                    mInfo, typeof(ObsoleteAttribute));
                if (obsAttr != null)
                    Console.WriteLine("The message is: \"{0}\".",
                        obsAttr.Message);
                else
                    Console.WriteLine("The message could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".
 */

open System

type TestClass() =
    // Assign the Obsolete attribute to a method.
    [<Obsolete "This method is obsolete. Use Method2 instead.">]
    member _.Method1() = ()
    member _.Method2() = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// See if the Obsolete attribute is defined for this method.
let isDef = Attribute.IsDefined(mInfo, typeof<ObsoleteAttribute>)

// Display the result.
printfn $"""The Obsolete Attribute {if isDef then "is" else "is not"} defined for {mInfo.Name} of class {clsType.Name}."""

// If it's defined, display the attribute's message.
if isDef then
    let obsAttr =
        Attribute.GetCustomAttribute(mInfo, typeof<ObsoleteAttribute>)
        :?> ObsoleteAttribute
    if obsAttr <> null then
        printfn $"The message is: \"{obsAttr.Message}\"."
    else
        printfn "The message could not be retrieved."

// Output:
//  The Obsolete Attribute is defined for Method1 of class TestClass.
// The message is: "This method is obsolete. Use Method2 instead.".

Imports System.Reflection

Module DemoModule

    Public Class TestClass
        ' Assign the Obsolete attribute to a method.
        <Obsolete("This method is obsolete. Use Method2() instead.")> _
        Public Sub Method1()
        End Sub

        Public Sub Method2()
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' See if the Obsolete attribute is defined for this method.
        Dim isDef As Boolean = Attribute.IsDefined(mInfo, _
            GetType(ObsoleteAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the results.
        Console.WriteLine("The Obsolete attribute {0} defined for " & _
            "method {1} of class {2}.", strDef, mInfo.Name, clsType.Name)
        ' If it's defined, display the attribute's message.
        If isDef = True Then
            Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo, _
                GetType(ObsoleteAttribute))
            If Not attr Is Nothing And TypeOf attr Is ObsoleteAttribute Then
                Dim obsAttr As ObsoleteAttribute = _
                    CType(attr, ObsoleteAttribute)
                Console.WriteLine("The message is: ""{0}""", obsAttr.Message)
            Else
                Console.WriteLine("The message could not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The Obsolete attribute is defined for method Method1 of class TestClass.
' The message is: "This method is obsolete. Use Method2() instead."

備註

從 .NET Framework 2.0 版本開始，若型別、方法或建構子在新中繼資料格式中儲存安全屬性，此方法會回傳 true。以版本 2.0 或更新編譯的組件會使用新格式。

適用於

IsDefined(Assembly, Type, Boolean)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷是否將任何自定義屬性套用至元件。參數會指定要搜尋的元件、要搜尋的自定義屬性類型，以及忽略的搜尋選項。

public:
 static bool IsDefined(System::Reflection::Assembly ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.Assembly element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.Assembly * Type * bool -> bool

Public Shared Function IsDefined (element As Assembly, attributeType As Type, inherit As Boolean) As Boolean

參數

element: Assembly

一個由描述可重用模組集合的 Assembly 類別衍生出來的物件。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

inherit: Boolean

此參數被忽略，且不影響此方法的運作。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

範例

以下程式碼範例說明了以為Assembly參數的使用 IsDefined。

using System;
using System.Reflection;

// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]
namespace IsDef1CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // Get the assembly object.
            Assembly assy = clsType.Assembly;
            // Store the assembly's name.
            String assyName = assy.GetName().Name;
            // See if the Assembly Description is defined.
            bool isdef = Attribute.IsDefined(assy,
                typeof(AssemblyDescriptionAttribute));
            if (isdef)
            {
                // Affirm that the attribute is defined.
                Console.WriteLine("The AssemblyDescription attribute " +
                    "is defined for assembly {0}.", assyName);
                // Get the description attribute itself.
                AssemblyDescriptionAttribute adAttr =
                    (AssemblyDescriptionAttribute)Attribute.GetCustomAttribute(
                    assy, typeof(AssemblyDescriptionAttribute));
                // Display the description.
                if (adAttr != null)
                    Console.WriteLine("The description is \"{0}\".",
                        adAttr.Description);
                else
                    Console.WriteLine("The description could not " +
                        "be retrieved.");
            }
            else
                Console.WriteLine("The AssemblyDescription attribute is not " +
                    "defined for assembly {0}.", assyName);
        }
    }
}

/*
 * Output:
 * The AssemblyDescription attribute is defined for assembly IsDef1CS.
 * The description is "A sample description".
 */

open System
open System.Reflection

// Add an AssemblyDescription attribute
[<assembly: AssemblyDescription "A sample description">]
do ()

type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// Get the assembly object.
let assembly = clsType.Assembly;

// Store the assembly's name.
let assemblyName = assembly.GetName().Name

// See if the Assembly Description is defined.
let isdef = 
    Attribute.IsDefined(assembly, typeof<AssemblyDescriptionAttribute>)

if isdef then
    // Affirm that the attribute is defined.
    printfn $"The AssemblyDescription attribute is defined for assembly {assemblyName}."
    
    // Get the description attribute itself.
    let adAttr =
        Attribute.GetCustomAttribute(assembly, typeof<AssemblyDescriptionAttribute>)
        :?> AssemblyDescriptionAttribute

    // Display the description.
    if adAttr <> null then
        printfn $"The description is \"{adAttr.Description}\"."
    else
        printfn $"The description could not be retrieved."
else
    printfn $"The AssemblyDescription attribute is not defined for assembly {assemblyName}."

// Output:
//  The AssemblyDescription attribute is defined for assembly IsDef1FS.
//  The description is "A sample description".

Imports System.Reflection

' Add an AssemblyDescription attribute.
<Assembly: AssemblyDescription("A sample description")> 

Module DemoModule
    Sub Main()
        ' Get the assembly for this module.
        Dim assy As System.Reflection.Assembly = GetType(DemoModule).Assembly
        ' Store the assembly name.
        Dim assyName As String = assy.GetName().Name
        ' See if the AssemblyDescription attribute is defined.
        If Attribute.IsDefined(assy, GetType(AssemblyDescriptionAttribute)) _
            Then
            ' Affirm that the attribute is defined. Assume the filename of
            ' this code example is "IsDef1VB".
            Console.WriteLine("The AssemblyDescription attribute is " & _
                "defined for assembly {0}.", assyName)
            ' Get the description attribute itself.
            Dim attr As Attribute = Attribute.GetCustomAttribute( _
                assy, GetType(AssemblyDescriptionAttribute))
            ' Display the description.
            If Not attr Is Nothing And _
                TypeOf attr Is AssemblyDescriptionAttribute Then
                Dim adAttr As AssemblyDescriptionAttribute = _
                    CType(attr, AssemblyDescriptionAttribute)
                Console.WriteLine("The description is " & _
                    Chr(34) & "{0}" & Chr(34) & ".", adAttr.Description)
            Else
                Console.WriteLine("The description could not be retrieved.")
            End If
        Else
            Console.WriteLine("The AssemblyDescription attribute is not " & _
                              "defined for assembly {0}.", assyName)
        End If
    End Sub
End Module

' Output:
' The AssemblyDescription attribute is defined for assembly IsDef1VB.
' The description is "A sample description".

備註

從 .NET Framework 2.0 版本開始，若組合語言中以新元資料格式儲存安全屬性，此方法會回傳 true。以版本 2.0 或更新編譯的組件會使用新格式。

適用於

IsDefined(MemberInfo, Type)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷是否將任何自定義屬性套用至型別的成員。參數會指定要搜尋的成員，以及要搜尋的自定義屬性類型。

public:
 static bool IsDefined(System::Reflection::MemberInfo ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.MemberInfo element, Type attributeType);

static member IsDefined : System.Reflection.MemberInfo * Type -> bool

Public Shared Function IsDefined (element As MemberInfo, attributeType As Type) As Boolean

參數

element: MemberInfo

一個從 MemberInfo 類別衍生出來的物件，描述類別中的建構子、事件、欄位、方法、型別或屬性成員。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

NotSupportedException

element 不是建構子、方法、屬性、事件、類型或欄位。

範例

以下程式碼範例說明了以 a MemberInfo 作為參數的使用IsDefined方法。

using System;
using System.Reflection;

namespace IsDef4CS
{
    public class TestClass
    {
        // Assign the Obsolete attribute to a method.
        [Obsolete("This method is obsolete. Use Method2 instead.")]
        public void Method1()
        {}
        public void Method2()
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // See if the Obsolete attribute is defined for this method.
            bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
            // Display the result.
            Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
                isDef ? "is" : "is not", mInfo.Name, clsType.Name);
            // If it's defined, display the attribute's message.
            if (isDef)
            {
                ObsoleteAttribute obsAttr =
                                 (ObsoleteAttribute)Attribute.GetCustomAttribute(
                                                    mInfo, typeof(ObsoleteAttribute));
                if (obsAttr != null)
                    Console.WriteLine("The message is: \"{0}\".",
                        obsAttr.Message);
                else
                    Console.WriteLine("The message could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".
 */

open System

type TestClass() =
    // Assign the Obsolete attribute to a method.
    [<Obsolete "This method is obsolete. Use Method2 instead.">]
    member _.Method1() = ()
    member _.Method2() = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// See if the Obsolete attribute is defined for this method.
let isDef = Attribute.IsDefined(mInfo, typeof<ObsoleteAttribute>)

// Display the result.
printfn $"""The Obsolete Attribute {if isDef then "is" else "is not"} defined for {mInfo.Name} of class {clsType.Name}."""

// If it's defined, display the attribute's message.
if isDef then
    let obsAttr =
        Attribute.GetCustomAttribute(mInfo, typeof<ObsoleteAttribute>)
        :?> ObsoleteAttribute
    if obsAttr <> null then
        printfn $"The message is: \"{obsAttr.Message}\"."
    else
        printfn "The message could not be retrieved."

// Output:
//  The Obsolete Attribute is defined for Method1 of class TestClass.
// The message is: "This method is obsolete. Use Method2 instead.".

Imports System.Reflection

Module DemoModule

    Public Class TestClass
        ' Assign the Obsolete attribute to a method.
        <Obsolete("This method is obsolete. Use Method2() instead.")> _
        Public Sub Method1()
        End Sub

        Public Sub Method2()
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' See if the Obsolete attribute is defined for this method.
        Dim isDef As Boolean = Attribute.IsDefined(mInfo, _
            GetType(ObsoleteAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the results.
        Console.WriteLine("The Obsolete attribute {0} defined for " & _
            "method {1} of class {2}.", strDef, mInfo.Name, clsType.Name)
        ' If it's defined, display the attribute's message.
        If isDef = True Then
            Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo, _
                GetType(ObsoleteAttribute))
            If Not attr Is Nothing And TypeOf attr Is ObsoleteAttribute Then
                Dim obsAttr As ObsoleteAttribute = _
                    CType(attr, ObsoleteAttribute)
                Console.WriteLine("The message is: ""{0}""", obsAttr.Message)
            Else
                Console.WriteLine("The message could not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The Obsolete attribute is defined for method Method1 of class TestClass.
' The message is: "This method is obsolete. Use Method2() instead."

備註

會搜尋的 element 祖先以尋找自訂屬性。

備註

適用於

IsDefined(Module, Type)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷指定型別的任何自定義屬性是否套用至模組。參數會指定要搜尋的模組，以及自定義屬性的類型。

public:
 static bool IsDefined(System::Reflection::Module ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.Module element, Type attributeType);

static member IsDefined : System.Reflection.Module * Type -> bool

Public Shared Function IsDefined (element As Module, attributeType As Type) As Boolean

參數

element: Module

一個由描述可攜式可執行檔案的 Module 類別衍生出來的物件。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

範例

以下程式碼範例說明了以 a Module 作為參數的使用IsDefined方法。

using System;
using System.Diagnostics;

// Add the Debuggable attribute to the module.
[module:Debuggable(true, false)]
namespace IsDef2CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // See if the Debuggable attribute is defined for this module.
            bool isDef = Attribute.IsDefined(clsType.Module,
                typeof(DebuggableAttribute));
            // Display the result.
            Console.WriteLine("The Debuggable attribute {0} " +
                "defined for Module {1}.",
                isDef ? "is" : "is not",
                clsType.Module.Name);
            // If the attribute is defined, display the JIT settings.
            if (isDef)
            {
                // Retrieve the attribute itself.
                DebuggableAttribute dbgAttr = (DebuggableAttribute)
                    Attribute.GetCustomAttribute(clsType.Module,
                    typeof(DebuggableAttribute));
                if (dbgAttr != null)
                {
                    Console.WriteLine("JITTrackingEnabled is {0}.",
                        dbgAttr.IsJITTrackingEnabled);
                    Console.WriteLine("JITOptimizerDisabled is {0}.",
                        dbgAttr.IsJITOptimizerDisabled);
                }
                else
                    Console.WriteLine("The Debuggable attribute " +
                        "could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Debuggable attribute is defined for Module IsDef2CS.exe.
 * JITTrackingEnabled is True.
 * JITOptimizerDisabled is False.
 */

open System
open System.Diagnostics

// Add the Debuggable attribute to the module.
[<``module``: Debuggable(true, false)>]
do ()
    
type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// See if the Debuggable attribute is defined for this module.
let isDef = Attribute.IsDefined(clsType.Module, typeof<DebuggableAttribute>)

// Display the result.
printfn $"""The Debuggable attribute {if isDef then "is" else "is not"} defined for Module {clsType.Module.Name}."""

// If the attribute is defined, display the JIT settings.
if isDef then
    // Retrieve the attribute itself.
    let dbgAttr =
        Attribute.GetCustomAttribute(clsType.Module, typeof<DebuggableAttribute>)
        :?> DebuggableAttribute

    if dbgAttr <> null then
        printfn $"JITTrackingEnabled is {dbgAttr.IsJITTrackingEnabled}."
        printfn $"JITOptimizerDisabled is {dbgAttr.IsJITOptimizerDisabled}."            
    else
        printfn "The Debuggable attribute could not be retrieved."

// Output:
//  The Debuggable attribute is defined for Module IsDef2CS.exe.
//  JITTrackingEnabled is True.
//  JITOptimizerDisabled is False.

Imports System.Reflection
Imports System.Diagnostics

' Add the Debuggable attribute to the module.
<Module: Debuggable(True, False)> 

Module DemoModule
    Sub Main()
        ' Get the module type information to access its metadata.
        Dim modType As Type = GetType(DemoModule)
        ' See if the Debuggable attribute is defined.
        Dim isDef As Boolean = Attribute.IsDefined(modType.Module, _
                               GetType(DebuggableAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the result
        Console.WriteLine("The debuggable attribute {0} defined for " & _
                          "module {1}.", strDef, modType.Name)
        ' If the attribute is defined, display the JIT settings.
        If isDef = True Then
            ' Retrieve the attribute itself.
            Dim attr As Attribute = _
                Attribute.GetCustomAttribute(modType.Module, _
                GetType(DebuggableAttribute))
            If Not attr Is Nothing And TypeOf attr Is DebuggableAttribute Then
                Dim dbgAttr As DebuggableAttribute = _
                    CType(attr, DebuggableAttribute)
                Console.WriteLine("JITTrackingEnabled is {0}.", _
                    dbgAttr.IsJITTrackingEnabled.ToString())
                Console.WriteLine("JITOptimizerDisabled is {0}.", _
                    dbgAttr.IsJITOptimizerDisabled.ToString())
            Else
                Console.WriteLine("The Debuggable attribute could " & _
                                  "not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The debuggable attribute is defined for module DemoModule.
' JITTrackingEnabled is True.
' JITOptimizerDisabled is False.

備註

的 element 祖先不會被搜尋為自訂屬性。

適用於

IsDefined(Assembly, Type)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷是否將任何自定義屬性套用至元件。參數會指定要搜尋的元件，以及自定義屬性的類型。

public:
 static bool IsDefined(System::Reflection::Assembly ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.Assembly element, Type attributeType);

static member IsDefined : System.Reflection.Assembly * Type -> bool

Public Shared Function IsDefined (element As Assembly, attributeType As Type) As Boolean

參數

element: Assembly

一個由描述可重用模組集合的 Assembly 類別衍生出來的物件。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

範例

以下程式碼範例說明了以為Assembly參數的使用 IsDefined。

using System;
using System.Reflection;

// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]
namespace IsDef1CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // Get the assembly object.
            Assembly assy = clsType.Assembly;
            // Store the assembly's name.
            String assyName = assy.GetName().Name;
            // See if the Assembly Description is defined.
            bool isdef = Attribute.IsDefined(assy,
                typeof(AssemblyDescriptionAttribute));
            if (isdef)
            {
                // Affirm that the attribute is defined.
                Console.WriteLine("The AssemblyDescription attribute " +
                    "is defined for assembly {0}.", assyName);
                // Get the description attribute itself.
                AssemblyDescriptionAttribute adAttr =
                    (AssemblyDescriptionAttribute)Attribute.GetCustomAttribute(
                    assy, typeof(AssemblyDescriptionAttribute));
                // Display the description.
                if (adAttr != null)
                    Console.WriteLine("The description is \"{0}\".",
                        adAttr.Description);
                else
                    Console.WriteLine("The description could not " +
                        "be retrieved.");
            }
            else
                Console.WriteLine("The AssemblyDescription attribute is not " +
                    "defined for assembly {0}.", assyName);
        }
    }
}

/*
 * Output:
 * The AssemblyDescription attribute is defined for assembly IsDef1CS.
 * The description is "A sample description".
 */

open System
open System.Reflection

// Add an AssemblyDescription attribute
[<assembly: AssemblyDescription "A sample description">]
do ()

type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// Get the assembly object.
let assembly = clsType.Assembly;

// Store the assembly's name.
let assemblyName = assembly.GetName().Name

// See if the Assembly Description is defined.
let isdef = 
    Attribute.IsDefined(assembly, typeof<AssemblyDescriptionAttribute>)

if isdef then
    // Affirm that the attribute is defined.
    printfn $"The AssemblyDescription attribute is defined for assembly {assemblyName}."
    
    // Get the description attribute itself.
    let adAttr =
        Attribute.GetCustomAttribute(assembly, typeof<AssemblyDescriptionAttribute>)
        :?> AssemblyDescriptionAttribute

    // Display the description.
    if adAttr <> null then
        printfn $"The description is \"{adAttr.Description}\"."
    else
        printfn $"The description could not be retrieved."
else
    printfn $"The AssemblyDescription attribute is not defined for assembly {assemblyName}."

// Output:
//  The AssemblyDescription attribute is defined for assembly IsDef1FS.
//  The description is "A sample description".

Imports System.Reflection

' Add an AssemblyDescription attribute.
<Assembly: AssemblyDescription("A sample description")> 

Module DemoModule
    Sub Main()
        ' Get the assembly for this module.
        Dim assy As System.Reflection.Assembly = GetType(DemoModule).Assembly
        ' Store the assembly name.
        Dim assyName As String = assy.GetName().Name
        ' See if the AssemblyDescription attribute is defined.
        If Attribute.IsDefined(assy, GetType(AssemblyDescriptionAttribute)) _
            Then
            ' Affirm that the attribute is defined. Assume the filename of
            ' this code example is "IsDef1VB".
            Console.WriteLine("The AssemblyDescription attribute is " & _
                "defined for assembly {0}.", assyName)
            ' Get the description attribute itself.
            Dim attr As Attribute = Attribute.GetCustomAttribute( _
                assy, GetType(AssemblyDescriptionAttribute))
            ' Display the description.
            If Not attr Is Nothing And _
                TypeOf attr Is AssemblyDescriptionAttribute Then
                Dim adAttr As AssemblyDescriptionAttribute = _
                    CType(attr, AssemblyDescriptionAttribute)
                Console.WriteLine("The description is " & _
                    Chr(34) & "{0}" & Chr(34) & ".", adAttr.Description)
            Else
                Console.WriteLine("The description could not be retrieved.")
            End If
        Else
            Console.WriteLine("The AssemblyDescription attribute is not " & _
                              "defined for assembly {0}.", assyName)
        End If
    End Sub
End Module

' Output:
' The AssemblyDescription attribute is defined for assembly IsDef1VB.
' The description is "A sample description".

備註

從 .NET Framework 2.0 版本開始，若組合語言中以新元資料格式儲存安全屬性，此方法會回傳 true。以版本 2.0 或更新編譯的組件會使用新格式。

適用於

IsDefined(ParameterInfo, Type)

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

來源:: Attribute.CoreCLR.cs

判斷是否將任何自定義屬性套用至方法參數。參數會指定要搜尋的方法參數，以及要搜尋的自定義屬性類型。

public:
 static bool IsDefined(System::Reflection::ParameterInfo ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.ParameterInfo element, Type attributeType);

static member IsDefined : System.Reflection.ParameterInfo * Type -> bool

Public Shared Function IsDefined (element As ParameterInfo, attributeType As Type) As Boolean

參數

element: ParameterInfo

一個從 ParameterInfo 類別衍生出來的物件，描述該類別成員的參數。

attributeType: Type

搜尋的自訂屬性的類型，或基底類型。

傳回

Boolean

true若對 ; 套用 element型別attributeType為的自訂屬性;否則， false

例外狀況

ArgumentNullException

element 或 attributeType 為 null。

ArgumentException

attributeType 並非由推導而來 Attribute。

範例

以下程式碼範例說明了以 a ParameterInfo 作為參數的使用IsDefined方法。

using System;
using System.Reflection;

namespace IsDef5CS
{
    public class TestClass
    {
        // Assign a ParamArray attribute to the parameter using the keyword.
        public void Method1(params String[] args)
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // Get the ParameterInfo array for the method parameters.
            ParameterInfo[] pInfo = mInfo.GetParameters();
            if (pInfo != null)
            {
                // See if the ParamArray attribute is defined.
                bool isDef = Attribute.IsDefined(pInfo[0],
                                                 typeof(ParamArrayAttribute));
                // Display the result.
                Console.WriteLine("The ParamArray attribute {0} defined for " +
                                  "parameter {1} of method {2}.",
                                  isDef ? "is" : "is not",
                                  pInfo[0].Name,
                                  mInfo.Name);
            }
            else
                Console.WriteLine("The parameters information could " +
                            "not be retrieved for method {0}.", mInfo.Name);
        }
    }
}

/*
 * Output:
 * The ParamArray attribute is defined for parameter args of method Method1.
 */

open System;

type TestClass() =
    // Assign a ParamArray attribute to the parameter.
    member _.Method1([<ParamArray>] args: string[]) = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// Get the ParameterInfo array for the method parameters.
let pInfo = mInfo.GetParameters()

if pInfo <> null then
    // See if the ParamArray attribute is defined.
    let isDef = Attribute.IsDefined(pInfo[0], typeof<ParamArrayAttribute>)

    // Display the result.
    printfn $"""The ParamArray attribute {if isDef then "is" else "is not"} defined for parameter {pInfo[0].Name} of method {mInfo.Name}."""
else
    printfn $"The parameters information could not be retrieved for method {mInfo.Name}."

// Output:
//  The ParamArray attribute is defined for parameter args of method Method1.

Imports System.Reflection

Module DemoModule
    Public Class TestClass
        ' Assign a ParamArray attribute to the parameter using the keyword.
        Public Sub Method1(ByVal ParamArray args As String())
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' Get the ParameterInfo array for the method parameters.
        Dim pInfo() As ParameterInfo = mInfo.GetParameters()
        If Not pInfo(0) Is Nothing Then
            ' See if the ParamArray attribute is defined.
            Dim isDef As Boolean = Attribute.IsDefined(pInfo(0), _
                                   GetType(ParamArrayAttribute))
            Dim strDef As String
            If isDef = True Then
                strDef = "is"
            Else
                strDef = "is not"
            End If
            ' Display the result.
            Console.WriteLine("The ParamArray attribute {0} defined " & _
                              "for parameter {1} of method {2}.", _
                              strDef, pInfo(0).Name, mInfo.Name)
        Else
            Console.WriteLine("Could not retrieve parameter information " & _
                              "for method {0}.", mInfo.Name)
        End If
    End Sub
End Module

' Output:
' The ParamArray attribute is defined for parameter args of method Method1.

備註

會搜尋的 element 祖先以尋找自訂屬性。

適用於

意見反應

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