Tuple<T1,T2,T3,T4,T5>.IStructuralEquatable.Equals Method
Definition
Important
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Returns a value that indicates whether the current Tuple<T1,T2,T3,T4,T5> 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 a DoubleComparer class that implements the IEqualityComparer interface. The example instantiates two Tuple<T1,T2,T3,T4,T5> objects by using a random number generator to populate their second through fifth components, casts the first instance to an IStructuralEquatable interface, and then uses a DoubleComparer object to test the two Tuple<T1,T2,T3,T4,T5> objects for approximate equality.
using System;
using System.Collections;
public class DoubleComparer<T1, T2, T3, T4, T5> : IEqualityComparer
{
private double difference;
private int argument = 0;
public DoubleComparer(double difference)
{
this.difference = difference;
}
new public bool Equals(object x, object y)
{
argument += 1;
// Return true for Item1.
if (argument == 1) return true;
double d1 = (double) x;
double d2 = (double) y;
if (d1 - d2 < d1 * difference)
return true;
else
return false;
}
public int GetHashCode(object obj)
{
if (obj is T1)
return ((T1) obj).GetHashCode();
else if (obj is T2)
return ((T2) obj).GetHashCode();
else if (obj is T3)
return ((T3) obj).GetHashCode();
else if (obj is T4)
return ((T4) obj).GetHashCode();
else
return ((T5) obj).GetHashCode();
}
}
public class Example
{
public static void Main()
{
var value1 = GetValues(1);
var value2 = GetValues(2);
IStructuralEquatable iValue1 = value1;
Console.WriteLine("{0} =\n{1} :\n{2}", value1, value2,
iValue1.Equals(value2,
new DoubleComparer<int, double, double, double, double>(.01)));
}
private static Tuple<int, double, double, double, double> GetValues(int ctr)
{
// Generate four random numbers between 0 and 1
Random rnd = new Random((int)DateTime.Now.Ticks >> 32 >> ctr);
return Tuple.Create(ctr, rnd.NextDouble(), rnd.NextDouble(),
rnd.NextDouble(), rnd.NextDouble());
}
}
open System
open System.Collections
type DoubleComparer<'T1, 'T2, 'T3, 'T4, 'T5 when 'T1: equality and 'T2: equality and 'T3: equality and 'T4: equality and 'T5: equality>(difference: double) =
let mutable argument = 0
interface IEqualityComparer with
member _.Equals(x, y) =
argument <- argument + 1
// Return true for Item1.
if argument = 1 then
true
else
let d1 = x :?> double
let d2 = y :?> double
d1 - d2 < d1 * difference
member _.GetHashCode(obj) =
match obj with
| :? 'T1 as obj -> obj.GetHashCode()
| :? 'T2 as obj -> obj.GetHashCode()
| :? 'T3 as obj -> obj.GetHashCode()
| :? 'T4 as obj -> obj.GetHashCode()
| _ -> (obj :?> 'T5).GetHashCode()
let getValues ctr =
// Generate four random numbers between 0 and 1
let rnd = Random(DateTime.Now.Ticks >>> 32 >>> ctr |> int)
Tuple.Create(ctr, rnd.NextDouble(), rnd.NextDouble(), rnd.NextDouble(), rnd.NextDouble())
let value1 = getValues 1
let value2 = getValues 2
let iValue1 = value1
printfn $"{value1} =\n{value2} :\n{(DoubleComparer<int, double, double, double, double> 0.01 :> IEqualityComparer).Equals(iValue1, value2)}"
Imports System.Collections
Public Class DoubleComparer(Of T1, T2, T3, T4, T5) : Implements IEqualityComparer
Private difference As Double
Private argument As Integer = 0
Public Sub New(difference As Double)
Me.difference = difference
End Sub
Public Overloads Function Equals(x As Object, y As Object) As Boolean _
Implements IEqualityComparer.Equals
argument += 1
' Return true for Item1.
If argument = 1 Then
Return True
Else
Dim d1 As Double = CDbl(x)
Dim d2 As Double = CDbl(y)
If d1 - d2 < d1 * difference Then
Return True
Else
Return False
End If
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()
ElseIf TypeOf obj Is T3 Then
Return CType(Obj, T3).GetHashCode()
ElseIf TypeOf obj Is T4 Then
Return CType(Obj, T4).GetHashCode()
Else
Return CType(obj, T5).GetHashCode()
End If
End Function
End Class
Module Example
Public Sub Main()
Dim value1 = GetValues(1)
Dim value2 = GetValues(2)
Dim iValue1 As IStructuralEquatable = value1
Console.WriteLine("{0} ={3}{1} :{3}{2}", value1, value2, _
iValue1.Equals(value2, _
New DoubleComparer(Of Integer, Double, Double, Double, Double)(.01)), _
vbCrLf)
End Sub
Private Function GetValues(ctr As Integer) As Tuple(Of Integer, Double, Double, Double, Double)
' Generate four random numbers between 0 and 1
Dim rnd As New Random(CInt((DateTime.Now.Ticks >> 32) >> ctr))
Return Tuple.Create(ctr, rnd.NextDouble(), rnd.NextDouble(),
rnd.NextDouble(), rnd.NextDouble)
End Function
End Module
' The example displays output like the following:
' (1, 0.910850029862882, 0.894596965934428, 0.319678635019659, 0.801647342649124) =
' (2, 0.818546649915421, 0.355961162762698, 0.0438506622071614, 0.679904267042831) :
' False
Remarks
This member is an explicit interface member implementation. It can be used only when the Tuple<T1,T2,T3,T4,T5> 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,T4,T5> 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> 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> objects. This continues until the method call returns false when it compares a specific pair of Item values, or the two Item5 values are passed to the method.
