Per the C#9 record proposal, the following should compile, even if not very useful without actual implementations.. // No explicit IEquatable<R> – this is synthesized! public sealed record SimpleVo { // Not virtual, as SimpleVo (R) is sealed. // Accepts SimpleVo? (R?), and not SimpleVo (R), as argument. public bool Equals(SimpleVo? other) => throw new … Read more
A case class implements the equals method for you while a class does not. Hence, when you compare two objects implemented as a class, instead of case class, what you’re comparing is the memory address of the objects. It’s really the same issues as when you have to deal with equality in Java. See this … Read more
Implementing equality in .NET correctly, efficiently and without code duplication is hard. Specifically, for reference types with value semantics (i.e. immutable types that treat equvialence as equality), you should implement the System.IEquatable<T> interface, and you should implement all the different operations (Equals, GetHashCode and ==, !=). As an example, here’s a class implementing value equality: … Read more
if ((a == b) && (b == c)) { … they’re all equal … } by the transitive relation
No. You can’t modify the equality operator and there is no built-in way to add support for custom types to use == syntax. Instead you should compare the pointer values using reflect.DeepEqual. Go supports equality checking structs. type Person struct { Name string } a := Person{“Bill DeRose”} b := Person{“Bill DeRose”} a == b … Read more
You can have a look at the type ExpressionEqualityComparer that is used inside Linq to db4o. It implements the interface IEqualityComparer<T>, so it’s usable for generic collections, as well as for a standalone usage. It uses the type ExpressionComparison to compare two Expressions for equality, and HashCodeCalculation, to compute a hashcode from an Expression. It … Read more
Two String objects will always be unequal to each other. Note that JavaScript has string primitive values as well as a String constructor to create wrapper objects. All object equality comparisons (especially with ===) are carried out as a test for reference equality. References to two different objects will of course never be equal to … Read more
https://golang.org/pkg/strings/#EqualFold is the function you are looking for. It is used like this (example from the linked documentation): package main import ( “fmt” “strings” ) func main() { fmt.Println(strings.EqualFold(“Go”, “go”)) }
The problem with the stream-based version is that if the collection (and thus its stream) contains null elements, then the predicate will throw a NullPointerException when it tries to call equals on this null object. This could be avoided with boolean exists = names.stream().anyMatch(x -> Objects.equals(x, n)); But there is no practical advantage to be … Read more
To simplify comparison operators for objects with more than one state variable, create a method that returns all of the object’s state as an array. Then just compare the two states: class Thing def initialize(a, b, c) @a = a @b = b @c = c end def ==(o) o.class == self.class && o.state == … Read more