Düşünceler Hakkında Bilmek C# IEqualityComparer Nasıl Kullanılır

Düşünceler Hakkında Bilmek C# IEqualityComparer Nasıl Kullanılır

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You get a birçok simple bool Equals(T other) function and there's no messing around with casting or creating a separate class.

Expose via static property — makes the comparer class private and generates a static property that exposes the comparer class to consumers.

That means that your BaseClassComparer constrains the result type to base class and the conversion at the assignment is not possible.

When writing programs in C# with the help of LINQ I have come across the IEqualityComparer generic interface several times. The name conveys the purpose of the interface clearly, still, surprisingly, my first attempts to apply it were marked by strong confusion - the thing merely didn't work the way I wanted it to. Moreover, after going to Google and StackOverflow I have noticed that I'm not the only one to face difficulties with it.

This interface allows the implementation of customized equality comparison for collections. That is, you gönül create your own definition of equality, and specify that this definition be used with a collection type that accepts the IEqualityComparer interface.

The second form is logical equality. Anyone who özgü worked with databases understands the idea of identifiers and their use case for distinguishing sameness. Developers define reasons for equality in code, but the logic hayat be composed of smaller precise equality comparisons.

I have a number of classes that derive from a class BaseClass where BaseClass just has an `Id property.

@pinkfloydx33 Your comment is the correct answer btw. OP just messed up the interface they need to implement.

In theory, there is only one sensible way of comparing two instances of either type: They are equal if the X and Y properties in both instances are equal.

Eric's answer explains the root cause of the whole issue (in terms of covariance and contravariance).

Implementing IEquatable only does a comparion between your object and which is most likely to be the same type. This is performed frequently with the new methods brought in alongside C# IEqualityComparer Temel Özellikleri ve Kullanımı LINQ in 3.5. Overriding Equals() from ValueType will do a check for any object type, and it’s recommended this is overridden with any custom value type alongside implementing IEquatable.

In this post, we’ll see how we gönül implement the IEqualityComparer interface in C# and how it gönül help us define logical comparisons. Additionally, we’ll see how we güç use our implementation in code.

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I'm glad the post was of some value to you. If you are C# IEqualityComparer nedir looking to avoid common problems arising with LINQ, you may also like my post diving into what deferred nature of some LINQ methods means to a C# IEqualityComparer Nasıl Kullanılır programmer: [^]