Question

法典(可能为伪装):

Person p1 = new Person { First = "John", Last = "Smith" };
Person p2 = new Person { First = "Jane", Last = "Smith" };

我期待着这样做:

bool b1 = Person.CompareOn({"First", "Last"}, p1, p2) // false;
bool b2 = Person.CompareOn({"Last"}         , p1, p2) // true;

Is there a predefined method that does this? Or do I have to write one myself?

Answer 1

你们是否必须把财产名称定为指号而不是直接的?

您可以撰写自己的习俗::IEqualityComparer<T> 执行,进行预测,然后又给它一个编码>AndAlso,以得出另一个预测。我的第一部分是MiscUtil ,而其余的斜体太难以使用。

您这样说:

// The first argument here is only for the sake of type inference
var comparer = PropertyEqualityComparer.WithExample(p1, p => p.First)
                                       .AndAlso(p => p.Last);
bool equal = comparer.Equals(p1, p2);

或

var comparer = PropertyEqualityComparer<Person>.Create(p1, p => p.First)
                                               .AndAlso(p => p.Last);
bool equal = comparer.Equals(p1, p2);

不幸的是,你可以使用<条码>第。在这里,你可能希望每个预测都有不同的目标类型。

(如果可能的话,希望为每一种设想建立一个比较机构。)

Answer 2

在个人课程中:

public virtual bool Equals(Person obj){
        if (obj == null) return false;
        if (Equals(First, obj.First) == false) return false;
        if (Equals(Last, obj.Last) == false) return false;
        return true;
    }

然后,你可以说:

 if(person1.Equals(person2){
                    blah....
}

Answer 3

every class in C# derived from the main class: Object, and this have a method: equals(Object ), wich do the job. Is that method you should override

class Person {
     ...
     public bool Equals(Object o) {
          return (Person)o.LastName.Equals(this.LastName);
     }
 }

例如,你应检查“o”是否无效,即用最后名称对等值进行检查。

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