Re: RFR: 8261123: Augment discussion of equivalence classes in Object.equals and comparison methods [v6]
On Fri, 12 Feb 2021 23:31:04 GMT, Stuart Marks wrote:
>> Joe Darcy has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Fix typo.
>
> src/java.base/share/classes/java/math/BigDecimal.java line 99:
>
>> 97: * hold. The results of methods like {@link scale} and {@link
>> 98: * unscaledValue} will differ for numerically equal values with
>> 99: * different representations.
>
> While this text is correct and reasonable, it doesn't really explain _why_
> equals() considers the representation. One might assume incorrectly that the
> representation is internal only and doesn't affect computations. Of course it
> does affect computations, which is why I suggested the example. Maybe the
> example doesn't belong right here, in which case it's reasonable for this
> change to proceed. I think it would be good to put an example _somewhere_ of
> non-substitutability of numerical values with different representations.
> Maybe we could handle that separately.
I've filed DK-8261862: "Expand discussion of rationale for BigDecimal
equals/compareTo semantics" as a follow-up bug.
-
PR: https://git.openjdk.java.net/jdk/pull/2471
Re: RFR: 8261123: Augment discussion of equivalence classes in Object.equals and comparison methods [v6]
On Fri, 12 Feb 2021 22:52:06 GMT, Joe Darcy wrote: >> A follow-up of sorts to JDK-8257086, this change aims to improve the >> discussion of the relationship between Object.equals and compareTo and >> compare methods. The not-consistent-with-equals natural ordering of >> BigDecimal get more explication too. While updating Object, I added some >> uses of apiNote and implSpec, as appropriate. While a signum method did not >> exist when Comparable was added, it has existed for many years so I removed >> obsolete text that defined a "sgn" function to compute signum. >> >> Once the changes are agreed to, I'll reflow paragraphs and update the >> copyright years. > > Joe Darcy has updated the pull request incrementally with one additional > commit since the last revision: > > Fix typo. Marked as reviewed by rriggs (Reviewer). - PR: https://git.openjdk.java.net/jdk/pull/2471
Re: RFR: 8261123: Augment discussion of equivalence classes in Object.equals and comparison methods [v6]
On Fri, 12 Feb 2021 22:52:06 GMT, Joe Darcy wrote:
>> A follow-up of sorts to JDK-8257086, this change aims to improve the
>> discussion of the relationship between Object.equals and compareTo and
>> compare methods. The not-consistent-with-equals natural ordering of
>> BigDecimal get more explication too. While updating Object, I added some
>> uses of apiNote and implSpec, as appropriate. While a signum method did not
>> exist when Comparable was added, it has existed for many years so I removed
>> obsolete text that defined a "sgn" function to compute signum.
>>
>> Once the changes are agreed to, I'll reflow paragraphs and update the
>> copyright years.
>
> Joe Darcy has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Fix typo.
Marked as reviewed by smarks (Reviewer).
src/java.base/share/classes/java/math/BigDecimal.java line 99:
> 97: * hold. The results of methods like {@link scale} and {@link
> 98: * unscaledValue} will differ for numerically equal values with
> 99: * different representations.
While this text is correct and reasonable, it doesn't really explain _why_
equals() considers the representation. One might assume incorrectly that the
representation is internal only and doesn't affect computations. Of course it
does affect computations, which is why I suggested the example. Maybe the
example doesn't belong right here, in which case it's reasonable for this
change to proceed. I think it would be good to put an example _somewhere_ of
non-substitutability of numerical values with different representations. Maybe
we could handle that separately.
-
PR: https://git.openjdk.java.net/jdk/pull/2471
Re: RFR: 8261123: Augment discussion of equivalence classes in Object.equals and comparison methods [v6]
> A follow-up of sorts to JDK-8257086, this change aims to improve the > discussion of the relationship between Object.equals and compareTo and > compare methods. The not-consistent-with-equals natural ordering of > BigDecimal get more explication too. While updating Object, I added some uses > of apiNote and implSpec, as appropriate. While a signum method did not exist > when Comparable was added, it has existed for many years so I removed > obsolete text that defined a "sgn" function to compute signum. > > Once the changes are agreed to, I'll reflow paragraphs and update the > copyright years. Joe Darcy has updated the pull request incrementally with one additional commit since the last revision: Fix typo. - Changes: - all: https://git.openjdk.java.net/jdk/pull/2471/files - new: https://git.openjdk.java.net/jdk/pull/2471/files/41102f52..03f01e65 Webrevs: - full: https://webrevs.openjdk.java.net/?repo=jdk=2471=05 - incr: https://webrevs.openjdk.java.net/?repo=jdk=2471=04-05 Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod Patch: https://git.openjdk.java.net/jdk/pull/2471.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/2471/head:pull/2471 PR: https://git.openjdk.java.net/jdk/pull/2471
