C# IStructuralEquatable nedir Ile ilgili detaylı notlar
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Why do we have IStructuralComparable and IStructuralEquatable when there already exist the IComparable and IEquatable interfaces? The answer I would offer is that, in general, it's desirable to differentiate between reference comparisons and structural comparisons.
= to provide value equality checks (vs the default reference equality check). The MSDN documentation suggests you only do it for immutable types. There are also issues involving interfaces and operator overloading.
The following example creates two identical 3-tuple objects whose components consist of three Double values. The value of the second component is Double.NaN. The example then calls the Tuple.Equals method, and it calls the IStructuralEquatable.Equals method three times. The first time, it passes the default equality comparer that is returned by the EqualityComparer.
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.
Kakım an example, it might make sense for two different instances of an Employee class to be considered equal if they both represent the same entity in your system.
Structural equality means that two objects are equal because they have equal values. It differs from reference equality, which indicates that two object references are equal because they reference the same physical object. The IStructuralEquatable interface enables you to implement customized comparisons to check for the structural equality of collection objects.
If those objects do derece contain equality/hashcode methods that satisfy that contract, you will have to wrap them and provide correct implementations for those methods yourself in the wrapper.
We kişi also make our own container play well with these other containers by implementing these interfaces.
The first issue we see here is that this struct is mutable in that you güç actually change the veri later on via the set properties. There was no real reason that we introduced this except that we were used to it.
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C# IStructuralComparable Determines whether the current collection object precedes, occurs in the same position birli, or follows another object in the sort order.
The example on MSDN gives part of the answer here; it seems to be useful for heterogeneous equality, rather than C# IStructuralEquatable nerelerde kullanılıyor homogeneous equality - i.e. for testing whether two objects (/values) of potentially different types
Just look at the default ValueType.Equals(object) code that gets called otherwise. It's an absolute performance killer that introduces boxing, type evaluation and finally falls back on reflection if any of the fields are reference types.
Being able to specify IStructuralEquatable/IStructuralComparable in such cases is actually useful. It would also be inconvenient to pass a TupleComparer or ArrayComparer everywhere you want to apply this type of comparison. The two approaches are not mutually exclusive.