-
-
Save JonathanLoscalzo/6001c228c67bc344d07b58e8ba03b841 to your computer and use it in GitHub Desktop.
Improved Jimmy Bogard's ValueObject<T> which supports inheritance
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// Ordinary | |
public class SimpleDto : ValueObject<SimpleDto> | |
{ | |
public string Value { get; set; } | |
} | |
// With base class | |
public abstract class BaseDto<T> : ValueObject<T> | |
{ | |
public string BaseValue { get; set; } | |
} | |
public class DtoWithBase : BaseDto<DtoWithBase> | |
{ | |
public string Value { get; set; } | |
} | |
public class Program | |
{ | |
static void Main() | |
{ | |
var s1 = new SimpleDto { Value = "Sample" }; | |
var s2 = new SimpleDto { Value = "Sample" }; | |
var s3 = new SimpleDto { Value = "Sample2" }; | |
var e1 = s1 == s2; // true | |
var e2 = s1 == s3; // false | |
var d1 = new DtoWithBase { Value = "Sample", BaseValue = "Sample" }; | |
var d2 = new DtoWithBase { Value = "Sample", BaseValue = "Sample" }; | |
var d3 = new DtoWithBase { Value = "Sample", BaseValue = "Sample2" }; | |
var e3 = d1 == d2; // true | |
var e4 = d1 == d3; // false | |
} | |
} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
using System; | |
using System.Collections.Generic; | |
using System.Linq; | |
using System.Reflection; | |
// This base class comes from Jimmy Bogard, but with support of inheritance | |
// http://grabbagoft.blogspot.com/2007/06/generic-value-object-equality.html | |
public abstract class ValueObject<T> : IEquatable<T> | |
where T : ValueObject<T> | |
{ | |
public override bool Equals(object obj) | |
{ | |
if (obj == null) | |
return false; | |
var other = obj as T; | |
return Equals(other); | |
} | |
public override int GetHashCode() | |
{ | |
var fields = GetFields(this); | |
var startValue = 17; | |
var multiplier = 59; | |
return fields | |
.Select(field => field.GetValue(this)) | |
.Where(value => value != null) | |
.Aggregate( | |
startValue, | |
(current, value) => current * multiplier + value.GetHashCode()); | |
} | |
public virtual bool Equals(T other) | |
{ | |
if (other == null) | |
return false; | |
var t = GetType(); | |
var otherType = other.GetType(); | |
if (t != otherType) | |
return false; | |
var fields = GetFields(this); | |
foreach (var field in fields) | |
{ | |
var value1 = field.GetValue(other); | |
var value2 = field.GetValue(this); | |
if (value1 == null) | |
{ | |
if (value2 != null) | |
return false; | |
} | |
else if (!value1.Equals(value2)) | |
return false; | |
} | |
return true; | |
} | |
private static IEnumerable<FieldInfo> GetFields(object obj) | |
{ | |
var t = obj.GetType(); | |
var fields = new List<FieldInfo>(); | |
while (t != typeof(object)) | |
{ | |
if (t == null) continue; | |
fields.AddRange(t.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public)); | |
t = t.BaseType; | |
} | |
return fields; | |
} | |
public static bool operator ==(ValueObject<T> x, ValueObject<T> y) | |
{ | |
if (ReferenceEquals(x, y)) | |
{ | |
return true; | |
} | |
if (((object)x == null) || ((object)y == null)) | |
{ | |
return false; | |
} | |
return x.Equals(y); | |
} | |
public static bool operator !=(ValueObject<T> x, ValueObject<T> y) | |
{ | |
return !(x == y); | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment