我一直在研究IEqualityComparer和IEquitable。使用IEquatable的好处
从如这样的帖子中,两者之间的区别现在已经很清楚了。 “IEqualityComparer是一个对象类型的接口,用于对T类型的两个对象执行比较。”
以https://msdn.microsoft.com/en-us/library/ms132151(v=vs.110).aspx为例,IEqualityComparer的用途很简单明了。
我已经按照在https://dotnetcodr.com/2015/05/05/implementing-the-iequatable-of-t-interface-for-object-equality-with-c-net/的例子来解决如何使用它,我得到了下面的代码:
class clsIEquitable
{
public static void mainLaunch()
{
Person personOne = new Person() { Age = 6, Name = "Eva", Id = 1 };
Person personTwo = new Person() { Age = 7, Name = "Eva", Id = 1 };
//If Person didn't inherit from IEquatable, equals would point to different points in memory.
//This means this would be false as both objects are stored in different locations
//By using IEquatable on class it compares the objects directly
bool p = personOne.Equals(personTwo);
bool o = personOne.Id == personTwo.Id;
//Here is trying to compare and Object type with Person type and would return false.
//To ensure this works we added an overrides on the object equals method and it now works
object personThree = new Person() { Age = 7, Name = "Eva", Id = 1 };
bool p2 = personOne.Equals(personThree);
Console.WriteLine("Equatable Check", p.ToString());
}
}
public class Person : IEquatable<Person>
{
public int Id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public bool Equals(Person other)
{
if (other == null) return false;
return Id == other.Id;
}
//These are to support creating an object and comparing it to person rather than comparing person to person
public override bool Equals(object obj)
{
if (obj is Person)
{
Person p = (Person)obj;
return Equals(p);
}
return false;
}
public override int GetHashCode()
{
return Id;
}
}
我的问题是,为什么我会使用它吗?这似乎是很多额外的代码下面的简单版本(BOOL O):
//By using IEquatable on class it compares the objects directly
bool p = personOne.Equals(personTwo);
bool o = personOne.Id == personTwo.Id;
*你知道你想通过Id来比较个人。存储“Person”的任何随机集合应该如何知道? –
假设你想添加一个额外的指标来比较'Person's。然后怎样呢?你会去寻找所有两个'Person'进行比较并重构它们的实例,或者只是编辑Equals'实现?这是代码重用的一个典型示例。 – EvilTak
一旦它指出它就很简单!谢谢 – Jay1b