Tuple<T1, T2, T3, T4, T5, T6>.IStructuralEquatable.Equals Method

Returns a value that indicates whether the current Tuple<T1, T2, T3, T4, T5, T6> object is equal to a specified object based on a specified comparison method.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
Private Function Equals ( _
    other As Object, _
    comparer As IEqualityComparer _
) As Boolean Implements IStructuralEquatable.Equals
bool IStructuralEquatable.Equals(
    Object other,
    IEqualityComparer comparer
)

Parameters

  • other
    Type: System.Object
    The object to compare with this instance.

Return Value

Type: System.Boolean
true if the current instance is equal to the specified object; otherwise, false.

Implements

IStructuralEquatable.Equals(Object, IEqualityComparer)

Remarks

This member is an explicit interface member implementation. It can be used only when the Tuple<T1, T2, T3, T4, T5, T6> instance is cast to an IStructuralEquatable interface.

The IEqualityComparer.Equals implementation is called only if other is not nulla null reference (Nothing in Visual Basic), and if it can be successfully cast (in C#) or converted (in Visual Basic) to a Tuple<T1, T2, T3, T4, T5, T6> object whose components are of the same types as the current instance. The IStructuralEquatable.Equals(Object, IEqualityComparer) method first passes the Item1 values of the Tuple<T1, T2, T3, T4, T5, T6> objects to be compared to the IEqualityComparer.Equals implementation. If this method call returns true, the method is called again and passed the Item2 values of the two Tuple<T1, T2, T3, T4, T5, T6> objects. This continues until the method call returns false when it compares a specific pair of Item values, or the two Item6 values are passed to the method.

Examples

The following example defines a RateComparer class that performs a custom test for equality. If the values that are passed to its IStructuralEquatable.Equals method are of type Single or Double, the method tests for equality by using only up to three fractional digits. Otherwise, it simply calls the x parameter's Equals method. The example uses this IEqualityComparer implementation to determine whether four Tuple<T1, T2, T3, T4, T5, T6> objects that contain data on the rate of population change between 1960 and 2000 are equal.

Imports System.Collections

Public Class RateComparer(Of T1, T2, T3, T4, T5, T6) : Implements IEqualityComparer
   Private argument As Integer = 0

   Public Overloads Function Equals(ByVal x As Object, ByVal y As Object) As Boolean _
                   Implements IEqualityComparer.Equals
      argument += 1
      If argument = 1 Then
         Return True
      Else
         Dim fx, fy As Double
         If TypeOf x Is Double Or TypeOf x Is Single Then
            fx = CDbl(x)
            fy = CDbl(y)
            Return Math.Round(fx * 1000).Equals(Math.Round(fy * 1000))
         Else
            Return x.Equals(y)
         End If
      End If
   End Function

   Public Overloads Function GetHashCode(ByVal obj As Object) As Integer _
                    Implements IEqualityComparer.GetHashCode
      If TypeOf (obj) Is Single Or TypeOf (obj) Is Double Then
         Return Math.Round(CDbl(obj) * 1000).GetHashCode()
      Else
         Return obj.GetHashCode()
      End If
   End Function
End Class

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim rate1 = Tuple.Create("New York", .014505, -.1042733, _ 
                               .0354833, .093644, .0290792)
      Dim rate2 = Tuple.Create("Unknown City", .014505, -.1042733, _ 
                               .0354833, .093644, .0290792)
      Dim rate3 = Tuple.Create("Unknown City", .014505, -.1042733, _ 
                               .0354833, .093644, .029079)
      Dim rate4 = Tuple.Create("San Francisco", -.0332858, -.0512803, _ 
                               .0662544, .0728964, .0491912)
      Dim eq As IStructuralEquatable = rate1
      ' Compare first tuple with remaining two tuples.
      outputBlock.Text += String.Format("{0} = ", rate1.ToString()) & vbCrLf
      outputBlock.Text += String.Format("   {0} : {1}", rate2, _
                        eq.Equals(rate2, New RateComparer(Of String, Double, Double, Double, Double, Double)())) + vbCrLf
      outputBlock.Text += String.Format("   {0} : {1}", rate3, _
                        eq.Equals(rate3, New RateComparer(Of String, Double, Double, Double, Double, Double)())) + vbCrLf
      outputBlock.Text += String.Format("   {0} : {1}", rate4, _   
                        eq.Equals(rate4, New RateComparer(Of String, Double, Double, Double, Double, Double)())) + vbCrLF
   End Sub
End Module
' The example displays the following output:
'    (New York, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.0290792) =
'       (Unknown City, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.0290792) : True
'       (Unknown City, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.029079) : True
'       (San Francisco, -0.0332858, -0.0512803, 0.0662544, 0.0728964, 0.0491912) : False
using System;
using System.Collections;

public class RateComparer<T1, T2, T3, T4, T5, T6> : IEqualityComparer
{
   private int argument = 0;

   public new bool Equals(object x, object y)
   {
      argument++;
      if (argument == 1) return true;

      double fx, fy;
      if (x is Double || x is Single)
      {
         fx = (double)x;
         fy = (double)y;
         return Math.Round(fx * 1000).Equals(Math.Round(fy * 1000));
      }
      else
      {
         return x.Equals(y);
      }
   }

   public int GetHashCode(object obj)
   {
      if (obj is Single || obj is Double)
         return Math.Round(((double)obj) * 1000).GetHashCode();
      else
         return obj.GetHashCode();
   }
}

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      var rate1 = Tuple.Create("New York", .014505, -.1042733,
                               .0354833, .093644, .0290792);
      var rate2 = Tuple.Create("Unknown City", .014505, -.1042733,
                               .0354833, .093644, .0290792);
      var rate3 = Tuple.Create("Unknown City", .014505, -.1042733,
                               .0354833, .093644, .029079);
      var rate4 = Tuple.Create("San Francisco", -.0332858, -.0512803,
                               .0662544, .0728964, .0491912);
      IStructuralEquatable eq = rate1;
      // Compare first tuple with remaining two tuples.
      outputBlock.Text += String.Format("{0} = ", rate1.ToString()) + "\n";
      outputBlock.Text += String.Format("   {0} : {1}", rate2,
                        eq.Equals(rate2, new RateComparer<string, double, double, double, double, double>())) + "\n";
      outputBlock.Text += String.Format("   {0} : {1}", rate3,
                        eq.Equals(rate3, new RateComparer<string, double, double, double, double, double>())) + "\n";
      outputBlock.Text += String.Format("   {0} : {1}", rate4,
                        eq.Equals(rate4, new RateComparer<string, double, double, double, double, double>())) + "\n";
   }
}
// The example displays the following output:
//    (New York, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.0290792) =
//       (Unknown City, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.0290792) : True
//       (Unknown City, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.029079) : True
//       (San Francisco, -0.0332858, -0.0512803, 0.0662544, 0.0728964, 0.0491912) : False

Version Information

Silverlight

Supported in: 5, 4

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.