Attribute.GetHashCode Méthode

Définition

Espace de noms:

System

Assembly:

System.Runtime.dll

Source:

Attribute.cs

Retourne le code de hachage de cette instance.

public:
 override int GetHashCode();

public override int GetHashCode ();

override this.GetHashCode : unit -> int

Public Overrides Function GetHashCode () As Integer

Retours

Int32

Code de hachage d'un entier signé 32 bits.

Exemples

L’exemple de code suivant illustre l’utilisation de GetHashCode dans le contexte de Attribute.

using System;
using System.Reflection;
using System.Collections.Generic;

// A custom attribute to allow two authors per method.
public class AuthorsAttribute : Attribute
{
   protected string _authorName1;
   protected string _authorName2;

   public AuthorsAttribute(string name1, string name2)
   {
      _authorName1 = name1;
      _authorName2 = name2;
   }

   public string AuthorName1
   {
      get { return _authorName1; }
      set { _authorName1 = value; }
   }

   public string AuthorName2
   {
      get { return _authorName2; }
      set { _authorName2 = value; }
   }

   // Use the hash code of the string objects and xor them together.
   public override int GetHashCode()
   {
      return _authorName1.GetHashCode() ^ _authorName2.GetHashCode();
   }
}

// Provide the author names for each method of the class.
public class TestClass
{
  [Authors("Immanuel Kant", "Lao Tzu")]
  public void Method1()
  {}

  [Authors("Jean-Paul Sartre", "Friedrich Nietzsche")]
  public void Method2()
  {}

  [Authors("Immanuel Kant", "Lao Tzu")]
  public void Method3()
  {}

  [Authors("Jean-Paul Sartre", "Friedrich Nietzsche")]
  public void Method4()
  {}

  [Authors("Immanuel Kant", "Friedrich Nietzsche")]
  public void Method5()
  {}
}

class Example
{
   static void Main()
   {
      // Get the class type to access its metadata.
      Type clsType = typeof(TestClass);

      // Store author information in a list of tuples.
      var authorsInfo = new List<Tuple<String, AuthorsAttribute>>();

      // Iterate through all the methods of the class.
      foreach(var method in clsType.GetMethods())
      {
          // Get the Authors attribute for the method if it exists.
          AuthorsAttribute authAttr =
              (AuthorsAttribute)Attribute.GetCustomAttribute(
              method, typeof(AuthorsAttribute));
          if (authAttr != null)
             // Add the information to the author list.
             authorsInfo.Add(Tuple.Create(clsType.Name + "." + method.Name,
                                             authAttr));
      }

      // Iterate through the list
      bool[] listed = new bool[authorsInfo.Count];
      Console.WriteLine("Method authors:\n");

      for (int ctr = 0; ctr < authorsInfo.Count; ctr++) {
         var authorInfo = authorsInfo[ctr];
         if (!listed[ctr]) {
             Console.WriteLine("{0} and {1}", authorInfo.Item2.AuthorName1,
                                              authorInfo.Item2.AuthorName2);
             listed[ctr] = true;
             Console.WriteLine("   {0}", authorInfo.Item1);
             for (int ctr2 = ctr + 1; ctr2 < authorsInfo.Count; ctr2++) {
                 if (!listed[ctr2])
                    if (authorInfo.Item2.Equals(authorsInfo[ctr2].Item2)) {
                       Console.WriteLine("   {0}", authorsInfo[ctr2].Item1);
                       listed[ctr2] = true;
                    }
            }
         }
      }
   }
}
// The example displays the following output:
//       Method authors:
//
//       Immanuel Kant and Lao Tzu
//          TestClass.Method1
//          TestClass.Method3
//       Jean-Paul Sartre and Friedrich Nietzsche
//          TestClass.Method2
//          TestClass.Method4
//       Immanuel Kant and Friedrich Nietzsche
//          TestClass.Method5

open System
open System.Reflection
open System.Collections.Generic

// A custom attribute to allow two authors per method.
[<AllowNullLiteral>]
type AuthorsAttribute(authorName1, authorName2) =
    inherit Attribute()

    member val AuthorName1 = authorName1
    member val AuthorName2 = authorName2

    // Use the hash code of the string objects and xor them together.
    override _.GetHashCode() =
        authorName1.GetHashCode() ^^^ authorName2.GetHashCode()

// Provide the author names for each method of the class.
type TestClass() =
    [<Authors("Immanuel Kant", "Lao Tzu")>]
    member _.Method1() = ()

    [<Authors("Jean-Paul Sartre", "Friedrich Nietzsche")>]
    member _.Method2() = ()

    [<Authors("Immanuel Kant", "Lao Tzu")>]
    member _.Method3() = ()

    [<Authors("Jean-Paul Sartre", "Friedrich Nietzsche")>]
    member _.Method4() = ()

    [<Authors("Immanuel Kant", "Friedrich Nietzsche")>]
    member _.Method5() = ()

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

// Store author information in a array of tuples.
let authorsInfo = 
  [ // Iterate through all the methods of the class.
    for method in clsType.GetMethods() do
        // Get the Authors attribute for the method if it exists.
        let authAttr =
            Attribute.GetCustomAttribute(method, typeof<AuthorsAttribute>) :?> AuthorsAttribute

        if authAttr <> null then
            // Add the information to the author list.
            $"{clsType.Name}.{method.Name}", authAttr ]

// Iterate through the list
printfn "Method authors:\n"

authorsInfo
|> List.groupBy (fun (_, authors) -> authors.AuthorName1, authors.AuthorName2)
|> List.iter (fun ((name1, name2), authors) ->
    printfn $"{name1} and {name2}"
    for (methodName, _) in authors do
        printfn $"   {methodName}")

// The example displays the following output:
//       Method authors:
//
//       Immanuel Kant and Lao Tzu
//          TestClass.Method1
//          TestClass.Method3
//       Jean-Paul Sartre and Friedrich Nietzsche
//          TestClass.Method2
//          TestClass.Method4
//       Immanuel Kant and Friedrich Nietzsche
//          TestClass.Method5

Imports System.Reflection
Imports System.Collections.Generic

' A custom attribute to allow two authors per method.
<AttributeUsage(AttributeTargets.Method)> _
Public Class AuthorsAttribute : Inherits Attribute
   Protected _authorName1 As String
   Protected _authorName2 As String

   Public Sub New(name1 As String, name2 As String)
      _authorName1 = name1
      _authorName2 = name2
   End Sub

   Public Property AuthorName1() As String
      Get
          Return _authorName1
      End Get
      Set
          _authorName1 = AuthorName1
      End Set
   End Property

   Public Property AuthorName2() As String
      Get
          Return _authorName2
      End Get
      Set
          _authorName2 = AuthorName2
      End Set
   End Property

   Public Overrides Function Equals(obj As Object) As Boolean
      Dim auth As AuthorsAttribute = TryCast(obj, AuthorsAttribute)
      If auth Is Nothing Then Return False
      
      If (_authorName1 = auth._authorName1 And _authorName2 = auth._authorName2) Or
         (_authorName1 = auth._authorName2 And _authorName2 = auth._authorName1)
         Return True
      Else
         Return False
      End If 
   End Function

   ' Use the hash code of the string objects and Xor them together.
   Public Overrides Function GetHashCode() As Integer
      Return _authorName1.GetHashCode() Xor _authorName2.GetHashCode()
   End Function
End Class

' Provide the author names for each method of the class.
Public Class TestClass
   <Authors("Immanuel Kant", "Lao Tzu")> _
   Public Sub Method1()
   End Sub

   <Authors("Jean-Paul Sartre", "Friedrich Nietzsche")> _
   Public Sub Method2()
   End Sub

   <Authors("Immanuel Kant", "Lao Tzu")> _
   Public Sub Method3()
   End Sub

   <Authors("Jean-Paul Sartre", "Friedrich Nietzsche")> _
   Public Sub Method4()
   End Sub

   <Authors("Immanuel Kant", "Friedrich Nietzsche")> _
   Public Sub Method5()
   End Sub
End Class

Public Module Example
    Sub Main()
        ' Get the TestClass type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        
        ' Store author information in a list of tuples.
        Dim authorsInfo As New List(Of Tuple(Of String, AuthorsAttribute)) 
        ' Iterate through all the methods of the class.
        For Each method In clsType.GetMethods()
            ' Get the authors attribute information 
            Dim authAttr As AuthorsAttribute = CType(Attribute.GetCustomAttribute(method, GetType(AuthorsAttribute)),
                                                     AuthorsAttribute)
            If authAttr IsNot Nothing Then
                ' Add the information to the author list.
                authorsInfo.Add(Tuple.Create(clsType.Name + "." + method.Name,
                                             authAttr))
            End If
        Next

        ' Iterate through the list.
        Dim listed(authorsInfo.Count - 1) As Boolean 
        Console.WriteLine("Method authors:")
        Console.WriteLine()
        For ctr As Integer = 0 To authorsInfo.Count - 1
           Dim authorInfo = authorsInfo(ctr)
           If Not listed(ctr)
              Console.WriteLine("{0} and {1}", authorInfo.Item2.AuthorName1,
                                               authorInfo.Item2.AuthorName2)
              listed(ctr) = True
              Console.WriteLine("   {0}", authorInfo.Item1)
              For ctr2 As Integer = ctr + 1 To authorsInfo.Count - 1
                 If Not listed(ctr2) 
                    If authorInfo.Item2.Equals(authorsInfo(ctr2).Item2) Then
                       Console.WriteLine("   {0}", authorsInfo(ctr2).Item1)
                       listed(ctr2) = true  
                    End if
                 End If 
              Next  
           End If   
        Next
    End Sub
End Module
' The example displays the following output:
'       Method Authors:
'
'       Immanuel Kant and Lao Tzu
'          TestClass.Method1
'          TestClass.Method3
'       Jean-Paul Sartre and Friedrich Nietzsche
'          TestClass.Method2
'          TestClass.Method4
'       Immanuel Kant and Friedrich Nietzsche
'          TestClass.Method5