Also, if you're interested in predicate-based APIs for filtering Iterables, check out the FilteredIterable class in Commons' unreleased [functor] component.
Matt On Mon, Jan 16, 2012 at 9:50 AM, James Ring <s...@jdns.org> wrote: > I agree, I'm just saying you should seriously study the design of those > interfaces before you embark on a project like this. > > Adding a new API to a library like collections imposes a burden on > maintainers that far outweighs the initial cost of the implementation. You > should make sure the API is worth the cost. The guys on guava have spent > serious effort designing the APIs, it's just good software engineering to > duplicate as little of that effort as possible. > > As much as it may bother some people to hear it, I think commons should > cease feature additions on collections and fix bugs only. Guava is very > much superior, is favourably licensed and effort should be focused in one > place. > > Just my two cents. I'm not an active member of Jakarta commons, just an > interested third party. :-) > > Regards, > James > > -- sent from my phone, excuse typos > On Jan 16, 2012 3:00 AM, "Benedikt Ritter" <b...@systemoutprintln.de> wrote: > >> Am 15.01.2012 20:23, schrieb James Ring: >> >>> Google Guava has all this and more, and it doesn't require an extension to >>> ArrayList, any Iterable will do. >>> >>> http://google-collections.**googlecode.com/svn/trunk/** >>> javadoc/com/google/common/**collect/Iterables.html<http://google-collections.googlecode.com/svn/trunk/javadoc/com/google/common/collect/Iterables.html> >>> >> >> Hi James, >> >> thanks for the response! I agree with you, that google guava does the same >> and that it does it better. In fact I do think, that there are things, that >> guava does even better than commons collections. For example using >> generics... >> >> However, what I do not agree with, is that this means, that there is no >> need for an extension of commons collections. I mean, then ASF could also >> stop developing tomcat, because there are clearly other application servers >> out there, that provide all functionality that tomcat has and maybe more. >> >> The FAQs on how to contribute just say "if you see something that can be >> improved, create a patch". And not "...that can be improved, but has not >> yet been implemented in some other library". >> If "not implementing functionality, that has been implemented elsewhere" >> is a common policy of commons or of commons collections, then I would >> recommend to put this in the FAQs on how to contribute (although I think, >> that would be a very bad thing to do, as I pointed out above). >> >> Having all that said, I still think that linking Predicates to queries >> would be a real improvement for commons collections. And I still would like >> to contribute the functionality somehow. I see your point, that extending >> java base classes is not the best thing to do. But as I said: I am willing >> to make what ever adjustment is required (also it seems to me, that this >> means re-writing the hole thing from scratch ;-) >> >> So, what do you think? >> Regards >> Benedikt >> >> On Jan 15, 2012 3:59 AM, "Benedikt >> Ritter"<bene@systemoutprintln.**de<b...@systemoutprintln.de>> >>> wrote: >>> >>> Hi, >>>> >>>> I have written a small extension for java.util.ArrayList, that allows for >>>> qerrying Lists using (generic) predicates. In addition to that, I adapted >>>> org.springframework.data.jpa.****domain.Specifications class as a util >>>> to >>>> link predicates to queries. Here is how it works: >>>> >>>> QueryableList<Customer> qList = new QueryableArrayList<Customer>()****; >>>> qList.addAll(getCustomers()); >>>> qList.getAll(new Predicate<Customer>() { >>>> >>>> public boolean evaluate(Customer element) { >>>> if (element.getLastName().****startsWith("B")) { >>>> return true; >>>> } else { >>>> return false; >>>> } >>>> } >>>> }); >>>> >>>> This will give you a List containing all customers, that match the given >>>> predicate. Using the Query class, we can link predicates via AND and OR >>>> or >>>> simply neglect them (the next example assumes, that we have a static >>>> import >>>> of the not and where method and startsWith(String) and bornAfter(int) are >>>> util methods, that return predicates): >>>> >>>> List<Customer> queryResult = qList.getAll(not(startsWith("****B"))); >>>> queryResult = qList.getAll(where(startsWith(** >>>> **"B")).or(startsWith("C"))); >>>> queryResult = qList.getAll(where(startsWith(** >>>> **"B")).and(bornAfter(1980))); >>>> >>>> In addition to that, there are implementations of common collection >>>> methods using predicates: >>>> >>>> public boolean containsMatch(Predicate<E> predicate); >>>> public Iterator<E> matchIterator(Predicate<E> predicate); >>>> public boolean retainAllMatches(Predicate<E> predicate); >>>> public boolean removeAllMatches(Predicate<E> predicate); >>>> >>>> ...and common list methods: >>>> >>>> public int indexOfMatch(Predicate<E> predicate); >>>> public int lastIndexOfMatch(Predicate<E> predicate); >>>> >>>> I think QueryableCollections would fit nicely into commons collections, >>>> because as far as I know, commons collections only offers you the >>>> opportunity to validate if all elements in a collection match a given >>>> predicate. There is no possibility to easily query for objects matching >>>> some criteria. >>>> Having that said, I would like to contribute all source code of >>>> QueryableCollections. I am willing to make what ever changes are >>>> required. >>>> >>>> Here are some thinks that I think will need to be adjusted before >>>> contribution: >>>> - swtich from my generic Predicate implementation to >>>> org.apache.commons.****collections.Predicate, >>>> although I really would like to see generics in commons collections. It >>>> saves you all the instanceof statements. >>>> - As far as I can see commons collections does not extend classes from >>>> java.util.* but decorates them. As I said QueryableArrayList is an >>>> extension of ArrayList. If there is a general policy of not extending >>>> java >>>> base classes, this would have to be changed. >>>> - Re-Implement jUnit tests using jUnit 3.8.1 (instead of jUnit 4.1.0) >>>> - change licence agreement von LGPL to Apache License >>>> >>>> All source code (and example code) is available at github: >>>> HEAD: >>>> https://github.com/britter/****QueryableCollections<https://github.com/britter/**QueryableCollections> >>>> <https://**github.com/britter/**QueryableCollections<https://github.com/britter/QueryableCollections> >>>> > >>>> v0.1.0: >>>> https://github.com/britter/****QueryableCollections/tree/**<https://github.com/britter/**QueryableCollections/tree/**> >>>> stable-0.1.0<https://github.**com/britter/**QueryableCollections/tree/** >>>> stable-0.1.0<https://github.com/britter/QueryableCollections/tree/stable-0.1.0> >>>> > >>>> You can download a build from my blog: >>>> http://www.systemoutprintln.****de/wp-content/uploads/** >>>> collections-0.1.0.jar<http://**www.systemoutprintln.de/wp-** >>>> content/uploads/collections-0.**1.0.jar<http://www.systemoutprintln.de/wp-content/uploads/collections-0.1.0.jar> >>>> > >>>> >>>> I'm really exited to hear what you guys think of QueryableCollections. >>>> Regards >>>> Benedikt Ritter >>>> >>>> ------------------------------****----------------------------** >>>> --**--------- >>>> To unsubscribe, e-mail: >>>> dev-unsubscribe@commons.**apac**he.org<http://apache.org> >>>> <dev-unsubscribe@**commons.apache.org<dev-unsubscr...@commons.apache.org> >>>> > >>>> For additional commands, e-mail: dev-h...@commons.apache.org >>>> >>>> >>>> >>> >> >> ------------------------------**------------------------------**--------- >> To unsubscribe, e-mail: >> dev-unsubscribe@commons.**apache.org<dev-unsubscr...@commons.apache.org> >> For additional commands, e-mail: dev-h...@commons.apache.org >> >> --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
