Interface, which defines a generalized method that a value type or class implements to create a type-specific method for determining equality of instances.
Questions tagged [iequatable]
165 questions
9
votes
9 answers
Implement GetHashCode on a class that has wildcard Equatability
Suppose I want to be able to compare 2 lists of ints and treat one particular value as a wild card.
e.g.
If -1 is a wild card, then
{1,2,3,4} == {1,2,-1,4} //returns true
And I'm writing a class to wrap all this logic, so it implements IEquatable…
Brondahl
- 7,402
- 5
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- 74
9
votes
5 answers
Howto override List Contains
I want to compare a property instead of the entire object using a List[MyObject]. I therefore use IEquatable[MyObject] but the compiler still wants MyObject instead of the string property. Why?
Here is what I got:
public class AnyClass
{
public…
UNeverNo
- 549
- 3
- 8
- 29
8
votes
2 answers
Equals method implementation helpers (C#)
Everytime I write some data class, I usually spend so much time writing the IEquatable implementation.
The last class I wrote was something like:
public class Polygon
{
public Point[] Vertices { get; set; }
}
Implementing IEquatable was…
Jader Dias
- 88,211
- 155
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8
votes
3 answers
Why is Array.IndexOf not checking for IEquatable like List does?
Consider this code:
public static void Main()
{
var item = new Item { Id = 1 };
IList list = new List- { item };
IList array = new[] { item };
var newItem = new Item { Id = 1 };
var lIndex = list.IndexOf(newItem);
var…
Shimmy Weitzhandler
- 101,809
- 122
- 424
- 632
8
votes
1 answer
Class implementation of IEquatable for use as a key in a dictionary
I've got a class which consists of two strings and an enum. I'm trying to use instances of this class as keys in a dictionary. Unfortunately I don't seem to be implementing IEquatable properly. Here's how I've done it:
public enum CoinSide
{
…
user2823789
- 167
- 1
- 3
- 10
8
votes
3 answers
Is it important to override Equals if I'm implementing IEquatable?
I know the importance of overriding GetHashCode when implementing custom equality checks - for which I have implemented IEquality interface, and also the difference between generic and non-generic Equals as discussed here. Now is there a point to…
nawfal
- 70,104
- 56
- 326
- 368
7
votes
2 answers
Generic class that conforms to Comparable in Swift
I'm attempting to create a simple generic node class that conforms to the Comparable protocol so that I can easily compare nodes without accessing their key. When I attempt to write the < and == functions, however, the compiler doesn't seem to like…
Daniel Rushton
- 480
- 5
- 13
6
votes
3 answers
Implement IEquatable for POCO
I noticed that EF's DbSet.Add() is quite slow. A little googling turned up a SO answer that promises up to 180x performance gains:
https://stackoverflow.com/a/7052504/141172
However, I do not understand exactly how to implement IEquatable as…
Eric J.
- 147,927
- 63
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- 553
6
votes
8 answers
IEquatable Interface what to do when checking for null
I have implemented the IEquatable interface in a class with the following code.
public bool Equals(ClauseBE other)
{
if (this._id == other._id)
{
return true;
}
return…
Matthew Vines
- 27,253
- 7
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- 97
6
votes
3 answers
Should GetHashCode be implemented for IEquatable on mutable types?
I'm implementing IEquatable, and I am having difficulty finding consensus on the GetHashCode override on a mutable class.
The following resources all provide an implementation where GetHashCode would return different values during the object's…
Neo
- 4,145
- 6
- 53
- 76
6
votes
2 answers
Value vs. Reference equality in generic List.Contains()
Attempt #3 to simplify this question:
A generic List can contain any type - value or reference. When checking to see if a list contains an object, .Contains() uses the default EqualityComparer for type T, and calls .Equals() (is my…
James King
- 6,233
- 5
- 42
- 63
5
votes
2 answers
How to compare two IEnumerable in C# if I don't know the actual object type?
I'm struggling with implementing the IEquatable<> interface for a class. The class has a Parameter property that uses a generic type. Basically the class definition is like this:
public class MyClass : IEquatable>
{
public T…
Baldewin
- 1,613
- 2
- 16
- 23
5
votes
1 answer
Custom object using Except failing to use IEqualityComparer
here is the object code:
public class DlpItem : IEqualityComparer
{
public string Text { get; set; }
public int Id { get; set; }
public DlpItem(int pId)
{
Text = string.Empty;
Id = pId;
}
public…
Matthew Cox
- 13,566
- 9
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- 72
5
votes
2 answers
Testing for value equality between two interface instances in c#?
So I have an interface, lets call it IInterface.
public interface IInterface : IEquatable
{
string Name { get; set; }
int Number { get; }
Task Update();
}
Then I try and implement the interface in Implementation.
…
bodangly
- 2,473
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- 28
5
votes
1 answer
Compiler picking wrong overload calling IEquatable.Equals
In a performance sensitive program, I am attempting to explicitly call IEquatable.Equals() and not Object.Equals (to avoid boxing in my case). Despite my best efforts, the compiler is always choosing Object.Equals() instead - which I don't…
user5876832