ParameterInfo.IsDefined(Type, Boolean) 方法

定義

命名空間:

System.Reflection

組件:

System.Runtime.dll

來源:

ParameterInfo.cs

判斷是否已有指定之型別或其衍生型別的自訂屬性套用至此參數。

public:
 virtual bool IsDefined(Type ^ attributeType, bool inherit);

public virtual bool IsDefined (Type attributeType, bool inherit);

abstract member IsDefined : Type * bool -> bool
override this.IsDefined : Type * bool -> bool

Public Overridable Function IsDefined (attributeType As Type, inherit As Boolean) As Boolean

參數

attributeType

Type

要搜尋的 Type 物件。

inherit

Boolean

這個類型的物件會忽略這個引數。

傳回

Boolean

如果已有 attributeType 或其衍生型別的一個或多個執行個體套用至這個參數，則為 true，否則為 false。

實作

IsDefined(Type, Boolean)

例外狀況

ArgumentNullException

attributeType 為 null。

ArgumentException

attributeType 不是由 Common Language Runtime 提供的 Type 物件。

範例

下列範例會定義兩個自訂屬性和 MyAttributeMyDerivedAttribute 。 MyDerivedAttribute 衍生自 MyAttribute。 然後，此範例會將這些屬性套用至範例類別之方法的參數。

執行範例時，它會使用 IsDefined 方法來測試範例類別中所有方法的所有參數。 然後會顯示具有 MyAttribute 或 MyDerivedAttribute 的參數。

// System::Reflection::ParameterInfo::GetCustomAttributes(Type, bool)
// System::Reflection::ParameterInfo::IsDefined(Type, bool)
using namespace System;
using namespace System::Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets::Parameter)]
public ref class MyAttribute: public Attribute
{
private:
   String^ myName;

public:
   MyAttribute( String^ name )
   {
      myName = name;
   }

   property String^ Name 
   {
      String^ get()
      {
         return myName;
      }
   }
};

// Derive another custom attribute from MyAttribute.
[AttributeUsage(AttributeTargets::Parameter)]
public ref class MyDerivedAttribute: public MyAttribute
{
public:
   MyDerivedAttribute( String^ name ) : MyAttribute( name ) {}
};

// Define a class with a method that has three parameters. Apply
// MyAttribute to one parameter, MyDerivedAttribute to another, and
// no attributes to the third. 
public ref class MyClass1
{
public:
   void MyMethod( [MyAttribute("This is an example parameter attribute")] 
                  int i,
                  [MyDerivedAttribute("This is another parameter attribute")] 
                  int j,
                  int k ){}
};

void main()
{
   // Get the type of the class 'MyClass1'.
   Type^ myType = MyClass1::typeid;

   // Get the members associated with the class 'MyClass1'.
   array<MethodInfo^>^myMethods = myType->GetMethods();

   // For each method of the class 'MyClass1', display all the parameters
   // to which MyAttribute or its derived types have been applied.
   for each ( MethodInfo^ mi in myMethods )
   {
      // Get the parameters for the method.
      array<ParameterInfo^>^ myParameters = mi->GetParameters();
      if ( myParameters->Length > 0 )
      {
         Console::WriteLine("\nThe following parameters of {0} have MyAttribute or a derived type:", mi);
         for each ( ParameterInfo^ pi in myParameters)
         {
            if (pi->IsDefined(MyAttribute::typeid, false))
            {
               Console::WriteLine("Parameter {0}, name = {1}, type = {2}", 
                  pi->Position, pi->Name, pi->ParameterType);
            }
         }
      }
   }
}

/* This code example produces the following output:

The following parameters of Void MyMethod(Int32, Int32, Int32) have MyAttribute or a derived type:
Parameter 0, name = i, type = System.Int32
Parameter 1, name = j, type = System.Int32

The following parameters of Boolean Equals(System.Object) have MyAttribute or a derived type:
 */

using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets.Parameter)]
public class MyAttribute : Attribute
{
    private string myName;
    public MyAttribute(string name)
    {
        myName = name;
    }
    public string Name
    {
        get
        {
            return myName;
        }
    }
}

// Derive another custom attribute from MyAttribute
[AttributeUsage(AttributeTargets.Parameter)]
public class MyDerivedAttribute : MyAttribute
{
    public MyDerivedAttribute(string name) : base(name) {}
}

// Define a class with a method that has three parameters. Apply
// MyAttribute to one parameter, MyDerivedAttribute to another, and
// no attributes to the third.
public class MyClass1
{
    public void MyMethod(
        [MyAttribute("This is an example parameter attribute")]
        int i,
        [MyDerivedAttribute("This is another parameter attribute")]
        int j,
        int k )
    {
        return;
    }
}

public class MemberInfo_GetCustomAttributes
{
    public static void Main()
    {
        // Get the type of the class 'MyClass1'.
        Type myType = typeof(MyClass1);
        // Get the members associated with the class 'MyClass1'.
        MethodInfo[] myMethods = myType.GetMethods();

        // For each method of the class 'MyClass1', display all the parameters
        // to which MyAttribute or its derived types have been applied.
        foreach (MethodInfo mi in myMethods)
        {
            // Get the parameters for the method.
            ParameterInfo[] myParameters = mi.GetParameters();
            if (myParameters.Length > 0)
            {
                Console.WriteLine("\nThe following parameters of {0} have MyAttribute or a derived type: ", mi);
                foreach (ParameterInfo pi in myParameters)
                {
                    if (pi.IsDefined(typeof(MyAttribute), false))
                    {
                        Console.WriteLine("Parameter {0}, name = {1}, type = {2}",
                            pi.Position, pi.Name, pi.ParameterType);
                    }
                }
            }
        }
    }
}

/* This code example produces the following output:

The following parameters of Void MyMethod(Int32, Int32, Int32) have MyAttribute or a derived type:
Parameter 0, name = i, type = System.Int32
Parameter 1, name = j, type = System.Int32

The following parameters of Boolean Equals(System.Object) have MyAttribute or a derived type:
 */

Imports System.Reflection

' Define a custom attribute with one named parameter.
<AttributeUsage(AttributeTargets.Parameter)> _
Public Class MyAttribute
    Inherits Attribute
    Private myName As String

    Public Sub New(ByVal name As String)
        myName = name
    End Sub 

    Public ReadOnly Property Name() As String
        Get
            Return myName
        End Get
    End Property
End Class 

' Derive another custom attribute from MyAttribute
<AttributeUsage(AttributeTargets.Parameter)> _
Public Class MyDerivedAttribute
    Inherits MyAttribute

    Public Sub New(ByVal name As String)
        MyBase.New(name)
    End Sub 
End Class

' Define a class with a method that has three parameters. Apply
' MyAttribute to one parameter, MyDerivedAttribute to another, and
' no attributes to the third. 
Public Class MyClass1

    Public Sub MyMethod(<MyAttribute("This is an example parameter attribute")> _
                        ByVal i As Integer, _
                        <MyDerivedAttribute("This is another parameter attribute")> _
                        ByVal j As Integer, _
                        ByVal k As Integer)
        Return
    End Sub 
End Class 

Public Class MemberInfo_GetCustomAttributes

    Public Shared Sub Main()
        ' Get the type of the class 'MyClass1'.
        Dim myType As Type = GetType(MyClass1)
        ' Get the members associated with the class 'MyClass1'.
        Dim myMethods As MethodInfo() = myType.GetMethods()

        ' For each method of the class 'MyClass1', display all the parameters
        ' to which MyAttribute or its derived types have been applied.
        For Each mi As MethodInfo In myMethods
            ' Get the parameters for the method.
            Dim myParameters As ParameterInfo() = mi.GetParameters()
            If myParameters.Length > 0 Then
                Console.WriteLine(vbCrLf & "The following parameters of {0} have MyAttribute or a derived type: ", mi)
                For Each pi As ParameterInfo In myParameters
                    If pi.IsDefined(GetType(MyAttribute), False) Then
                        Console.WriteLine("Parameter {0}, name = {1}, type = {2}", _
                            pi.Position, pi.Name, pi.ParameterType)
                    End If
                Next
            End If
        Next
    End Sub 
End Class 

' This code example produces the following output:
'
'The following parameters of Void MyMethod(Int32, Int32, Int32) have MyAttribute or a derived type:
'Parameter 0, name = i, type = System.Int32
'Parameter 1, name = j, type = System.Int32
'
'The following parameters of Boolean Equals(System.Object) have MyAttribute or a derived type:

備註

這個方法會 inherit 忽略 參數。 若要搜尋繼承鏈結中的參數屬性，請使用 方法的適當 Attribute.IsDefined 多載。