Ok, I’ve raised the issue on esdiscuss now and I got an answer from Mozilla’s Jason Orendorff: This is a problem with ES6 maps. The solution will come in the form of ES7 value objects for keys instead of objects. It was considered before to let people specify .equals and .hashCode but it was rejected … Read more
Yes, you need to override isEqual (and hash) to make your objects fully Objective-C compatible. Here’s a Playground-ready example for the syntax: import Foundation class MyClass: NSObject { var value = 5 override func isEqual(object: AnyObject?) -> Bool { if let object = object as? MyClass { return value == object.value } else { return … Read more
If you need different behaviour when you’re dealing with a value-type then you’re obviously going to need to perform some kind of test. You don’t need an explicit check for boxed value-types, since all value-types will be boxed** due to the parameter being typed as object. This code should meet your stated criteria: If value … Read more
No. Consider the trivial monad: data Trivial a = Cow instance Monad Trivial where _ >>= _ = Cow return _ = Cow
In Ruby == is just a method (with some syntax sugar on top allowing you to write foo == bar instead of foo.==(bar)) and you override == just like you would any other method: class MyClass def ==(other_object) # return true if self is equal to other_object, false otherwise end end
Thats the is operator print f1 is f2
Why is the following code printing “Different.”? Because Arrays.equals performs a shallow comparison. Since arrays inherit their equals-method from Object, an identity comparison will be performed for the inner arrays, which will fail, since a and b do not refer to the same arrays. If you change to Arrays.deepEquals it will print “Equal.” as expected.
If Java 7+, use Objects.equals(); its documentation explicitly specifies that: […] if both arguments are null, true is returned and if exactly one argument is null, false is returned. Otherwise, equality is determined by using the equals method of the first argument. which is what you want. If you don’t, your method can be rewritten … Read more
KennyTM is correct, there is no other simpler or more efficient way. However, if you have many variables, you could also build an array of the values and use the IEnumerable.All method to verify they’re all 1. More readable, IMO. if (new[] { v1, v2, v3, v4, v5, v6, v7, v8, v9, v10 }.All(x => … Read more
I think trying to come up with some generally useful hash function that will generate unique hash values for collections is an exercise in futility. U62’s suggestion of combining the hashes of all the contents will not scale well, as it makes the hash function O(n). Hash functions should really be O(1) to ensure good … Read more