Bir İnceleme C# IStructuralEquatable Temel Özellikleri
Bir İnceleme C# IStructuralEquatable Temel Özellikleri
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Keep in mind that for this interface to work correctly, the types within the collection or structure must also implement IStructuralEquatable or provide their own structural equality logic.
In certain scenarios (such birli using the value type as a key in a dictionary) it dirilik murder performance in one foul swoop.
Other types which implement structural equality/comparability include tuples and anonymous types - which both clearly benefit from the ability to perform comparison based on their structure and content. A question you didn't ask is:
Daniel A.A. PelsmaekerDaniel A.A. Pelsmaeker 49.2k2121 gold badges112112 silver badges160160 bronze badges 5 In addition to answers which point to duplicate hashcodes bey is documented behavior, some reasoning and reflection would also lead you to the same conclusion.
You generic method katışıksız a type parameter T but the type is derece part of the signature of the function so how is T supposed to be used in the function? Anyway, you birey use .NET tuples or anonymous types to create hash codes by combining values but I am derece sure this answers your question.
The IStructuralEquatable interface enables you to implement customized comparisons to check for the structural equality of collection objects.
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Consider that there are only ~4.2 billion different hashcodes. Kişi you create more than this many different objects of the type on which GetHashCode is called? In this case it is easy to see the answer is "yes". So GetHashCode is a sort of compressing projection onto a smaller takım - there are bound to be duplicates.
Reading through the excellent blog post by Sergey on struct equality performance he mentions that the default implementations are pretty slow and using boxing for each member. Additionally, he mentions that a memory comparison may derece give you the correct results in this super simple example:
In all my years of development and blogging I never thought I would be writing about how amazing a C# struct is, how awesome IEquatable is, and how C# 7 features make implementing all of it mind blowing.
Each of your objects should use C# IStructuralEquatable Nasıl kullanılır a hashcode based on the contents of the object. If you have a value type containing 3 ints, use those when computing the hash code. Like this, all objects with identical content will have the same hash code, independent of app domain and other circumstances.
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Default property. The second time, it passes the default equality comparer that is returned by the StructuralComparisons.StructuralEqualityComparer property. The third time, it passes the custom NanComparer object. As the output from the example shows, the first three method calls return true, whereas the fourth call returns false.
However, this is not so great if you are using the struct in a dictionary bey my good friend Dustin mentioned to me because a Dictionary will always use the object version of Equals, which falls back to boxing :(