Tuple<T1,T2,T3>.IStructuralEquatable.Equals Method
Definition
Important
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Returns a value that indicates whether the current Tuple<T1,T2,T3> object is equal to a specified object based on a specified comparison method.
virtual bool System.Collections.IStructuralEquatable.Equals(System::Object ^ other, System::Collections::IEqualityComparer ^ comparer) = System::Collections::IStructuralEquatable::Equals;bool IStructuralEquatable.Equals (object other, System.Collections.IEqualityComparer comparer);abstract member System.Collections.IStructuralEquatable.Equals : obj * System.Collections.IEqualityComparer -> bool
override this.System.Collections.IStructuralEquatable.Equals : obj * System.Collections.IEqualityComparer -> boolFunction Equals (other As Object, comparer As IEqualityComparer) As Boolean Implements IStructuralEquatable.EqualsParameters
- other
- Object
The object to compare with this instance.
- comparer
- IEqualityComparer
An object that defines the method to use to evaluate whether the two objects are equal.
Returns
true if the current instance is equal to the specified object; otherwise, false.
Implements
Examples
The following example defines an Item2Comparer class that implements the IEqualityComparer interface and changes the way in which Tuple<T1,T2,T3> objects are evaluated for equality. The method always returns true when it is passed the Item1 property values of two Tuple<T1,T2,T3> objects, and it calls the Tuple<T1,T2,T3>.IStructuralEquatable.Equals method to evaluate their Item2 property values. If this method call returns true, their Item3 property values are passed to the method, which always returns true. As a result, the method tests for equality based only on the value of the Item2 property. The output illustrates the result for a data set of Tuple<T1,T2,T3> objects that record the names, mean test score, and number of tests of students in a class.
using System;
using System.Collections;
public class Item2Comparer<T1, T2, T3> : IEqualityComparer
{
new public bool Equals(object x, object y)
{
// Return true for all values of Item1.
if (x is T1)
return true;
else if (x is T2)
return x.Equals(y);
else
return true;
}
public int GetHashCode(object obj)
{
if (obj is T1)
return ((T1) obj).GetHashCode();
else if (obj is T2)
return ((T2) obj).GetHashCode();
else
return ((T3) obj).GetHashCode();
}
}
public class Example
{
public static void Main()
{
Tuple<string, double, int>[] scores =
{ Tuple.Create("Ed", 78.8, 8),
Tuple.Create("Abbey", 92.1, 9),
Tuple.Create("Jim", 71.2, 9),
Tuple.Create("Sam", 91.7, 8),
Tuple.Create("Sandy", 71.2, 5),
Tuple.Create("Penelope", 82.9, 8),
Tuple.Create("Serena", 71.2, 9),
Tuple.Create("Judith", 84.3, 9) };
for (int ctr = 0; ctr < scores.Length; ctr++)
{
IStructuralEquatable score = scores[ctr];
for (int ctr2 = ctr + 1; ctr2 < scores.Length; ctr2++)
{
Console.WriteLine("{0} = {1}: {2}", score,
scores[ctr2],
score.Equals(scores[ctr2],
new Item2Comparer<string, double, int>()));
}
Console.WriteLine();
}
}
}
// The example displays the following output:
// (Ed, 78.8, 8) = (Abbey, 92.1, 9): False
// (Ed, 78.8, 8) = (Jim, 71.2, 9): False
// (Ed, 78.8, 8) = (Sam, 91.7, 8): False
// (Ed, 78.8, 8) = (Sandy, 71.2, 5): False
// (Ed, 78.8, 8) = (Penelope, 82.9, 8): False
// (Ed, 78.8, 8) = (Serena, 71.2, 9): False
// (Ed, 78.8, 8) = (Judith, 84.3, 9): False
//
// (Abbey, 92.1, 9) = (Jim, 71.2, 9): False
// (Abbey, 92.1, 9) = (Sam, 91.7, 8): False
// (Abbey, 92.1, 9) = (Sandy, 71.2, 5): False
// (Abbey, 92.1, 9) = (Penelope, 82.9, 8): False
// (Abbey, 92.1, 9) = (Serena, 71.2, 9): False
// (Abbey, 92.1, 9) = (Judith, 84.3, 9): False
//
// (Jim, 71.2, 9) = (Sam, 91.7, 8): False
// (Jim, 71.2, 9) = (Sandy, 71.2, 5): True
// (Jim, 71.2, 9) = (Penelope, 82.9, 8): False
// (Jim, 71.2, 9) = (Serena, 71.2, 9): True
// (Jim, 71.2, 9) = (Judith, 84.3, 9): False
//
// (Sam, 91.7, 8) = (Sandy, 71.2, 5): False
// (Sam, 91.7, 8) = (Penelope, 82.9, 8): False
// (Sam, 91.7, 8) = (Serena, 71.2, 9): False
// (Sam, 91.7, 8) = (Judith, 84.3, 9): False
//
// (Sandy, 71.2, 5) = (Penelope, 82.9, 8): False
// (Sandy, 71.2, 5) = (Serena, 71.2, 9): True
// (Sandy, 71.2, 5) = (Judith, 84.3, 9): False
//
// (Penelope, 82.9, 8) = (Serena, 71.2, 9): False
// (Penelope, 82.9, 8) = (Judith, 84.3, 9): False
//
// (Serena, 71.2, 9) = (Judith, 84.3, 9): False
open System
open System.Collections
type Item2Comparer<'T1, 'T2, 'T3 when 'T1: equality and 'T2: equality and 'T3: equality>() =
interface IEqualityComparer with
member _.Equals(x: obj, y: obj) =
// Return true for all values of Item1.
match x with
| :? 'T1 ->
true
| :? 'T2 ->
x.Equals y
| _ -> true
member _.GetHashCode(obj: obj) =
match obj with
| :? 'T1 as obj->
obj.GetHashCode()
| :? 'T2 as obj ->
obj.GetHashCode()
| _ ->
(obj :?> 'T3).GetHashCode()
let scores =
[| Tuple.Create("Ed", 78.8, 8)
Tuple.Create("Abbey", 92.1, 9)
Tuple.Create("Jim", 71.2, 9)
Tuple.Create("Sam", 91.7, 8)
Tuple.Create("Sandy", 71.2, 5)
Tuple.Create("Penelope", 82.9, 8)
Tuple.Create("Serena", 71.2, 9)
Tuple.Create("Judith", 84.3, 9) |]
for ctr = 0 to scores.Length - 1 do
let score : IStructuralEquatable = scores[ctr]
for ctr2 = ctr + 1 to scores.Length - 1 do
printfn $"{score} = {scores[ctr2]}: {score.Equals(scores[ctr2], Item2Comparer<string, double, int>())}"
printfn ""
// The example displays the following output:
// (Ed, 78.8, 8) = (Abbey, 92.1, 9): False
// (Ed, 78.8, 8) = (Jim, 71.2, 9): False
// (Ed, 78.8, 8) = (Sam, 91.7, 8): False
// (Ed, 78.8, 8) = (Sandy, 71.2, 5): False
// (Ed, 78.8, 8) = (Penelope, 82.9, 8): False
// (Ed, 78.8, 8) = (Serena, 71.2, 9): False
// (Ed, 78.8, 8) = (Judith, 84.3, 9): False
//
// (Abbey, 92.1, 9) = (Jim, 71.2, 9): False
// (Abbey, 92.1, 9) = (Sam, 91.7, 8): False
// (Abbey, 92.1, 9) = (Sandy, 71.2, 5): False
// (Abbey, 92.1, 9) = (Penelope, 82.9, 8): False
// (Abbey, 92.1, 9) = (Serena, 71.2, 9): False
// (Abbey, 92.1, 9) = (Judith, 84.3, 9): False
//
// (Jim, 71.2, 9) = (Sam, 91.7, 8): False
// (Jim, 71.2, 9) = (Sandy, 71.2, 5): True
// (Jim, 71.2, 9) = (Penelope, 82.9, 8): False
// (Jim, 71.2, 9) = (Serena, 71.2, 9): True
// (Jim, 71.2, 9) = (Judith, 84.3, 9): False
//
// (Sam, 91.7, 8) = (Sandy, 71.2, 5): False
// (Sam, 91.7, 8) = (Penelope, 82.9, 8): False
// (Sam, 91.7, 8) = (Serena, 71.2, 9): False
// (Sam, 91.7, 8) = (Judith, 84.3, 9): False
//
// (Sandy, 71.2, 5) = (Penelope, 82.9, 8): False
// (Sandy, 71.2, 5) = (Serena, 71.2, 9): True
// (Sandy, 71.2, 5) = (Judith, 84.3, 9): False
//
// (Penelope, 82.9, 8) = (Serena, 71.2, 9): False
// (Penelope, 82.9, 8) = (Judith, 84.3, 9): False
//
// (Serena, 71.2, 9) = (Judith, 84.3, 9): False
Imports System.Collections
Public Class Item2Comparer(Of T1, T2, T3) : Implements IEqualityComparer
Public Overloads Function Equals(x As Object, y As Object) As Boolean _
Implements IEqualityComparer.Equals
' Return true for all values of Item1.
If TypeOf x Is T1 Then
Return True
ElseIf TypeOf x Is T2 Then
Return x.Equals(y)
Else
Return True
End If
End Function
Public Overloads Function GetHashCode(obj As Object) As Integer _
Implements IEqualityComparer.GetHashCode
If TypeOf obj Is T1 Then
Return CType(obj, T1).GetHashCode()
ElseIf TypeOf obj Is T2 Then
Return CType(obj, T2).GetHashCode()
Else
Return CType(obj, T3).GetHashCode()
End If
End Function
End Class
Module Example
Public Sub Main()
Dim scores() =
{ Tuple.Create("Ed", 78.8, 8),
Tuple.Create("Abbey", 92.1, 9),
Tuple.Create("Jim", 71.2, 9),
Tuple.Create("Sam", 91.7, 8),
Tuple.Create("Sandy", 71.2, 5),
Tuple.Create("Penelope", 82.9, 8),
Tuple.Create("Serena", 71.2, 9),
Tuple.Create("Judith", 84.3, 9) }
For ctr As Integer = 0 To scores.Length - 1
Dim score As IStructuralEquatable = scores(ctr)
For ctr2 As Integer = ctr + 1 To scores.Length - 1
Console.WriteLine("{0} = {1}: {2}", score,
scores(ctr2),
score.Equals(scores(ctr2),
new Item2Comparer(Of String, Double, Integer)))
Next
Console.WriteLine()
Next
End Sub
End Module
' The example displays the following output:
' (Ed, 78.8, 8) = (Abbey, 92.1, 9): False
' (Ed, 78.8, 8) = (Jim, 71.2, 9): False
' (Ed, 78.8, 8) = (Sam, 91.7, 8): False
' (Ed, 78.8, 8) = (Sandy, 71.2, 5): False
' (Ed, 78.8, 8) = (Penelope, 82.9, 8): False
' (Ed, 78.8, 8) = (Serena, 71.2, 9): False
' (Ed, 78.8, 8) = (Judith, 84.3, 9): False
'
' (Abbey, 92.1, 9) = (Jim, 71.2, 9): False
' (Abbey, 92.1, 9) = (Sam, 91.7, 8): False
' (Abbey, 92.1, 9) = (Sandy, 71.2, 5): False
' (Abbey, 92.1, 9) = (Penelope, 82.9, 8): False
' (Abbey, 92.1, 9) = (Serena, 71.2, 9): False
' (Abbey, 92.1, 9) = (Judith, 84.3, 9): False
'
' (Jim, 71.2, 9) = (Sam, 91.7, 8): False
' (Jim, 71.2, 9) = (Sandy, 71.2, 5): True
' (Jim, 71.2, 9) = (Penelope, 82.9, 8): False
' (Jim, 71.2, 9) = (Serena, 71.2, 9): True
' (Jim, 71.2, 9) = (Judith, 84.3, 9): False
'
' (Sam, 91.7, 8) = (Sandy, 71.2, 5): False
' (Sam, 91.7, 8) = (Penelope, 82.9, 8): False
' (Sam, 91.7, 8) = (Serena, 71.2, 9): False
' (Sam, 91.7, 8) = (Judith, 84.3, 9): False
'
' (Sandy, 71.2, 5) = (Penelope, 82.9, 8): False
' (Sandy, 71.2, 5) = (Serena, 71.2, 9): True
' (Sandy, 71.2, 5) = (Judith, 84.3, 9): False
'
' (Penelope, 82.9, 8) = (Serena, 71.2, 9): False
' (Penelope, 82.9, 8) = (Judith, 84.3, 9): False
'
' (Serena, 71.2, 9) = (Judith, 84.3, 9): False
Remarks
This member is an explicit interface member implementation. It can be used only when the Tuple<T1,T2,T3> instance is cast to an IStructuralEquatable interface.
The IEqualityComparer.Equals implementation is called only if other is not null, and if it can be successfully cast (in C#) or converted (in Visual Basic) to a Tuple<T1,T2,T3> object whose components are of the same types as the current instance. The Tuple<T1,T2,T3>.IStructuralEquatable.Equals method first passes the Item1 values of the Tuple<T1,T2,T3> 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> objects. If this method call returns true again, the method is called a third time and passed the Item3 values of the two Tuple<T1,T2,T3> objects.
