EMDD.KtSourceGen.KtEquatable 1.0.0.1

EMDD.KtEquatable

use of C# 9.0 Source Generator to AutoGenerate IEquatable<T> using attributes.

Usage

The source generator can be used by marking the target class with [Equatable] Attribute. The properties can also be marked with specific attributes specify the equality comparison method to be used. The sample below shows an EmployeeInfo class marked with the specific Attributes.

using EMDD.KtSourceGen.KtEquatable.Core;

[Equatable]
partial class EmployeeInfo
{
    public string? Name { get; set; }
    
    [IgnoreEquality]
    public int Id { get; set; }

    [FloatingPointEquality(Precision = 4)]
    public double Salary { get; set; }

    [UnorderedEquality]
    public Dictionary<string, int>? BankAccountDetails { get; set; }

    [OrderedEquality]
    public List<DateTime>? TimeIn { get; set; }

    [ReferenceEquality]
    public EmployeeInfo? Superior { get; set; }

    [ReferenceEquality]
    public string? SocialSecurity { get; set; }
}

class Program
{
    static void Main(string[] args)
    {
        const string SS = "BBB";
        
        EmployeeInfo boss1 = new EmployeeInfo() { Name = "Bob", Id = 1 };
        EmployeeInfo boss2 = new EmployeeInfo() { Name = "Bob", Id = 2 };
        EmployeeInfo employee1 = new EmployeeInfo() {
            Name = "Chipotle",
            Id = 3,
            Salary = 10000.0003,
            BankAccountDetails = new Dictionary<string, int> { { "Wells", 123 }, { "JP", 234 }, { "BoA", 345 } },
            Superior = boss1,
            TimeIn= new List<DateTime> { new DateTime (2012,3,4), new DateTime(2012, 3, 5), new DateTime(2012, 3, 6) },
            SocialSecurity="AAA"
        };
        EmployeeInfo employee2 = new EmployeeInfo() {
            Name = "Chipotle",
            Id = 3,
            Salary = 10000.0003,
            BankAccountDetails = new Dictionary<string, int> { { "Wells", 123 }, { "JP", 234 }, { "BoA", 345 } },
            Superior = boss2,
            TimeIn= new List<DateTime> { new DateTime (2012,3,4), new DateTime(2012, 3, 5), new DateTime(2012, 3, 6)},
            SocialSecurity= SS
        };
        EmployeeInfo employee3 = new EmployeeInfo() {
            Name = "Chipotle",
            Id = 3,
            Salary = 10000.0004,
            BankAccountDetails = new Dictionary<string, int> { { "Wells", 123 }, { "JP", 234 }, { "BoA", 345 } },
            Superior = boss2,
            TimeIn= new List<DateTime> { new DateTime (2012,3,4), new DateTime(2012, 3, 5), new DateTime(2012, 3, 6) },
            SocialSecurity = SS
        };
        Console.WriteLine(employee1 != employee2);
        Console.WriteLine(employee2 == employee3);
    }
}

Supported Attributes

Equatable

The code generator will only recognize class orrecordmarked with [Equatable].

Default

A property that is not marked by any Attributes mentioned below will produce a generated code that uses EqualityComparer<T>.Default when checking Equality and calculating Hashcode.

IgnoreEquality

Properties marked with [IgnoreEquality] will not be included in the equality checking and Hashcode calculation

[IgnoreEquality] 
public string Name { get; set; }

FloatingPointEquality

[FloatingPointEquality(Precision = 10)]
public double Salary { get; set; } // Must be double

A property marked with [FloatingPointEquality] will be used in the comparison of equality such that the difference between the compared value should not be less than the precision. the property will be equal if:

System.Math.Abs(_value1.Salary - _value2.Salary) < System.Math.Pow(10,-Precision)

The hashcode is also computed by rounding off the value of the property

System.Math.Round(Salary * System.Math.Pow(10,Precision), 0).GetHashCode();

OrderedEquality, UnorderedEquality, and SetEquality

Comparison of Collections/IEnumerables with specific requirements such as when the order is not or is required or if the collection can have repeated elements.

[Equatable]
partial class Book 
{
    [OrderedEquality] 
    public DateTime[] Borrower { get; set; } 

    [UnorderedEquality] 
    public string[] BookTitle { get; set; } 

    [SetEquality] 
    public HashSet<string> Borrowers { get; set; }
}

ReferenceEquality

A property marked with [ReferenceEquality] will use Reference equality checking only

[ReferenceEquality]
public Employee Superior { get; set; }