Fix HashDict so that key comparison uses exact match #1177
Conversation
|
Jamie, couldn't we leave the Dict "ordered" but simply stop using keyfind I put ordered in between quotes because just the buckets are ordered. Thank you! José Valim |
|
Oops, iPhone autocompleted James into Jamie. :) José Valim |
This change means that HashDict buckets are nolonger strictly ordered. Previously keys which compared equal (==) but not exactly equal (===) would be considered different for large sizes but equivalent for small sizes. This ambiguity occured because hashes are only equal when terms are exactly equal (===), so both now use exact (===) key comparisons. Small HashDicts are still a single ordered list and large HashDicts contain ordered buckets. Both of these may contain keys that compare equal (==) but are not exactly equal (===), should these keys be present in the same list or bucket the ordering of these keys (relative to each other) is undefined. See github issue elixir-lang#1171 for examples. Note: If assumptions were made about the form of a HashDict they may nolonger be valid. Particularly that HashDicts can nolonger be reliably pattern matched on for equality.
|
Forgot to reply saying I'd updated the PR. On 3 June 2013 01:05, José Valim notifications@github.com wrote:
|
Fix HashDict so that key comparison uses exact match
|
@josevalim can you please make a hotfix release (say 0.9.1) with this fix? I think the bug was bad enough to warrant a release. In particular, I'll depend entirely on |
|
@alexrp Yes, I agree on a release. I just need time as I am oversees right now and there is one extra small thing I want to include in this release. |
|
OK, thanks! |
This change means that a HashDict is nolonger ordered. Previously
HashDicts did some ordering and for small sizes were fully ordered.
However this meant that keys which compared equal (==) but not exactly
equal (===) would be considered different for large sizes but
equivalent for small sizes. This ambiguity occured because hashes are
only equal when terms are exactly equal (===).
See github issue #1171 for examples, and #1175 for some discussion.
Note: If assumptions were made about the form of a HashDict they may
nolonger be valid. Particularly that HashDicts can nolonger be reliably
pattern matched on for equality.
Sorry for the issue spam, can't get the github API to work to add a PR to existing issue.