On Fri, Dec 18, 2015 at 10:38 PM, Steven D'Aprano steve@pearwood.info wrote:
On Fri, Dec 18, 2015 at 05:59:39PM -0500, Franklin? Lee wrote:
I see two options:
- comparison is explicitly NotImplemented. Any code that used it
should've used `is`.
We're still talking about equality between Mapping.values() views, correct?
I strongly dislike that option. I don't know of any std lib or built-in object which tries to prohibit equality comparisons. Of course your own custom classes can do anything they like, including rather silly things:
class Silly: def __eq__(self, other): x = random.choice([0, 1, 2]) if x == 2: raise ValueError return bool(x)
but I think that people expect that equality tests should always succeed, even if it falls back on the default object behaviour (namely identity comparison).
First, failing fast. I see this as a silent error waiting to happen.
Second, "NotImplemented" allows the other side to try its __eq__.
- comparison respects keys.
I'm not sure I understand what this means. If we have two dicts:
a = {1: None, 2: None} b = {1: None, 3: None}
are you suggesting that `a.values() == b.values()` should return False because the KEYS {1, 2} and {1, 3} are different?
Yes, I'm just saying that's an option.