PRs are welcome :-) Gary
On Wed, May 4, 2022, 08:09 Steve Bosman <stevebos...@gmail.com> wrote: > I've started working somewhere where I can work on opensource during > downtime. I can see this has been open a while and I'm happy to pick it up. > I'm thinking one PR with some javadoc clarifications to the original method > for three or more booleans, and if still wanted another PR with the > requested function. > > Would that be okay? > > Steve > > On Tue, 29 Dec 2020, 19:34 Alberto Scotto (Jira), <j...@apache.org> wrote: > > > > > [ > > > https://issues.apache.org/jira/browse/LANG-1627?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17256142#comment-17256142 > > ] > > > > Alberto Scotto commented on LANG-1627: > > -------------------------------------- > > > > {quote}[https://en.wikipedia.org/wiki/XOR_gate#More_than_two_inputs] > > {quote} > > Interesting! So there exists one such boolean function which works as I > > expect. > > > > BTW, my use case is the following: > > > > I have a web service which accepts a request with a number of fields, say > > 3, with the constraint that exactly one among the 3 fields must be not > null. > > > > I think it's a pretty common scenario, so it would make sense to add this > > other semantic of xor to BooleanUtils. We may call it xorOneHot. I would > be > > keen on keeping "xor" in the name so that users can find it when using > > autocompletion and are looking for "xor". > > > > I'm working on an implementation already. Just shout if you'd like me to > > submit a PR. > > > > > BooleanUtils.xor not behaving as expected with any odd number of true's > > > ----------------------------------------------------------------------- > > > > > > Key: LANG-1627 > > > URL: https://issues.apache.org/jira/browse/LANG-1627 > > > Project: Commons Lang > > > Issue Type: Bug > > > Affects Versions: 3.11 > > > Reporter: Alberto Scotto > > > Priority: Major > > > > > > Hi, > > > I was expecting a xor function that takes a variable number of > arguments > > to *return true if and only if exactly one among all of the arguments is > > true*, regardless of the number of arguments. > > > This holds true given three false's: > > > {code:java} > > > @Test > > > public void threeFalse() { > > > boolean[] bools = new boolean[]{Boolean.FALSE, Boolean.FALSE, > > Boolean.FALSE}; > > > assertFalse(BooleanUtils.xor(bools)); > > > }{code} > > > > > > It also holds true given 4 true's, as well as for any even number of > > trues. > > > {code:java} > > > @Test > > > public void fourTrue() { > > > boolean[] bools = new boolean[]{Boolean.TRUE, Boolean.TRUE, > > Boolean.TRUE, Boolean.TRUE}; > > > assertFalse(BooleanUtils.xor(bools)); > > > } > > > {code} > > > The above tests pass. > > > But with any odd number of true's that doesn't hold anymore: > > > > > > {code:java} > > > @Test > > > public void threeTrue() { > > > boolean[] bools = new boolean[]{Boolean.TRUE, Boolean.TRUE, > > Boolean.TRUE}; > > > assertFalse(BooleanUtils.xor(bools)); > > > } > > > {code} > > > This test fails. > > > That was totally unexpected to me. > > > But as it turns out, even > > > {noformat} > > > true ^ true ^ true{noformat} > > > evaluates to true. That was unexpected too to me, at a first sight. > > > The thing is that xor (I mean the original boolean operator) is a > binary > > operator, so if you want to make it n-ary, one simple solution is to > apply > > it in two by two: ((a ^ b) ^ c) ^ d > > > And that's what is done in the implementation of the method > > BooleanUtils#xor. > > > But that brings to BooleanUtils.xor(true, true, true) == true, and at > > the same time BooleanUtils.xor(true, true, true, true) == false, which > just > > doesn't sound right to me. > > > Whether or not you agree with me that that is a bug of the method, > > please at least update the Javadoc, because right now it is not providing > > the user enough information. Look: > > > {code:java} > > > Performs an xor on a set of booleans. > > > BooleanUtils.xor(true, true) = false > > > BooleanUtils.xor(false, false) = false > > > BooleanUtils.xor(true, false) = true > > > {code} > > > > > > Thanks. > > > Cheers > > > > > > > > -- > > This message was sent by Atlassian Jira > > (v8.3.4#803005) > > >
