Thanks for the fast response!
Replacing the == definition with
override func isEqual(object: AnyObject?) -> Bool {
guard let object = object as? KeyType2 else { return false }
return id == object.id
}
fixed this issue!
Etan
On 17 Dec 2015, at 23:48, Dmitri Gribenko
<[email protected]<mailto:[email protected]>> wrote:
On Thu, Dec 17, 2015 at 2:17 PM, Etan Kissling via swift-users
<[email protected]<mailto:[email protected]>> wrote:
I want to use instances of a custom class as Dictionary key.
This requires the class to conform to Hashable.
func ==(lhs: KeyType1, rhs: KeyType1) -> Bool { return lhs.id == rhs.id }
final class KeyType1: Hashable, CustomStringConvertible {
let id: String
init(id: String) { self.id = id }
var hashValue: Int { return id.hashValue }
var description: String { return id }
}
Now I can use KeyType1 instances as key in Dictionary.
var collection1 = [KeyType1(id: "foo") : NSObject()]
Testing works fine:
let key = collection1.first!.0
print(" Key stored in collection: \(unsafeAddressOf(key)) -- \(key)")
let keyCopy = KeyType1(id: key.id)
print(" Key copy: \(unsafeAddressOf(keyCopy)) --
\(keyCopy)")
print(" Keys equal: \(key == keyCopy)")
print(" Hash values equal: \(key.hashValue ==
keyCopy.hashValue)")
print(" Collection has item for key: \(collection1[key] != nil)")
print("Collection has item for key copy: \(collection1[keyCopy] != nil)")
Key stored in collection: 0x0000608000043d80 -- foo
Key copy: 0x00006080000440b0 -- foo
Keys equal: true
Hash values equal: true
Collection has item for key: true
Collection has item for key copy: true
Next, I repeat the same set up -- but this time KeyType is a descendant of
NSObject.
func ==(lhs: KeyType2, rhs: KeyType2) -> Bool { return lhs.id == rhs.id }
final class KeyType2: NSObject { // NSObject conforms to Hashable and
CustomStringConvertible.
let id: String
init(id: String) { self.id = id; super.init() }
override var hashValue: Int { return id.hashValue }
override var description: String { return id }
}
Again, I create a Dictionary based on this key class.
var collection2 = [KeyType2(id: "foo") : NSObject()]
Using the same tests, they fail now.
let key = collection2.first!.0
print(" Key stored in collection: \(unsafeAddressOf(key)) -- \(key)")
let keyCopy = KeyType2(id: key.id)
print(" Key copy: \(unsafeAddressOf(keyCopy)) --
\(keyCopy)")
print(" Keys equal: \(key == keyCopy)")
print(" Hash values equal: \(key.hashValue ==
keyCopy.hashValue)")
print(" Collection has item for key: \(collection2[key] != nil)")
print("Collection has item for key copy: \(collection2[keyCopy] != nil)")
Key stored in collection: 0x0000608000044080 -- foo
Key copy: 0x00006080000440e0 -- foo
Keys equal: true
Hash values equal: true
Collection has item for key: true
Collection has item for key copy: false
What am I missing here?
The == overload in the second case is not the one that gets put into the
protocol witness table. When you call == on two instances of your type, upcast
to NSObject, the isEqual() method is called.
We are aware of this issue and it will be fixed when we move operators into
types.
Dmitri
--
main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
(j){printf("%d\n",i);}}} /*Dmitri Gribenko
<[email protected]<mailto:[email protected]>>*/
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