Paul Haddad
Jeff Kelley
@tapbot_paul Probably because -hashValue does not guarantee uniqueness. Without this, putting NSData in a collection would take ages.
TIL NSData only uses the first 80 bytes to hash itself and doesn’t use length at all for some reason.
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@SlaunchaMan ^= _length would hardly add any time to it. -
@tapbot_paul True. I wonder if -length has any weird performance penalties?
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@tapbot_paul same for NSString. First 80 characters or so. -
@bdkjones NSString does take length into account though. -
@tapbot_paul Collisions still possible. Strings of same >80 length with identical first 80 characters. Edge case, but possible. -
@bdkjones@tapbot_paul I think it’s first, last and middle 32 characters for NSString.
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@tapbot_paul prepend the length to the data, voila! Unique hashes. hashtag-programming! -
@DigDoug@tapbot_paul nope. Possible for two datas of same >80 length to have identical first 80 bytes. Not safe in all cases.
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@tapbot_paul the hash of nsarray is just its length. -
@tapbot_paul Maybe length isn’t always O(1) to calculate? Does NSData have a generator API? -
@tapbot_paul that seems rather counter to what one might want to do with NSData.
Bryan Jones
Karsten Bruns
DigDoug
Christian Kienle
Frederic Barthelemy
Wayne Dixon
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