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Matt On Sun, Mar 2, 2014 at 10:46 AM, Dipanjan Laha <dipanja...@gmail.com> wrote: > Hi Thomas, > > I have implemented the MultiValuedMap interface, the MultiValuedHashMap > and a MultiValuedHashMapTest as per the discussions. I haven't completed > the documentation yet. If the implementations look fine, I will add the > remaining documentations. > > A few more points regarding the implementation > > 1. I have added a few methods to the MultiValuedMap interface which were > not there in the MultiMap. I think they would be a good addition to the > interface IMHO. They are > boolean containsValue(Object key, Object value); > int totalSize(); > void putAll(MultiValuedMap<? extends K, ? extends V> map); > 2. I have added an AbstractMultiValuedMapDecoractor on the lines > of AbstractMapDecorator, which can be extended by other MultiValuedMap > implementations like say a MultiValuedTreeMap > 3. I have created MultiValuedGet and MultiValuedPut to honor the Get/Put > split concepts. It was not possible for MultiValuedMap to extend the Get & > Put directly due to the limitations I had mentioned in my earlier mail. > 4. I have marked the incomplete documentations with TODO tags. > > PFA the patch for the new Classes. Please go through the implementation > and let me know if I missed some thing or if things need to be done in some > other way. > > Regards > Dipanjan > > > > On Wed, Feb 26, 2014 at 8:04 PM, Dipanjan Laha <dipanja...@gmail.com>wrote: > >> Thanks for pointing this out. However, implementing Get & Put directly >> would pose the following problems. >> >> If interface MultiValuedMap<K,V> extends Get<K,Collection<V>> >> >> the method "values" would be forced to have a signature of >> >> Collection<Collection<V>> values() >> >> whereas we would want >> >> Collection<V> values(). >> >> This wont be possible as we would extend Get with the generics >> <K,Collection<V>> as we want the method "get" to have a signature like >> >> Collection<V> get(Object key) >> >> Now, extending the Put interface with generics <K,V> does not pose that >> much of an issue except that the Map interface in Java 7 has a put >> signature as V put(K key, V value) whereas the Collections 4 Put still has >> Object put(Key k, V value), but we can ignore this if we want. >> >> For the problem with Get, we can have a parallel MultiValuedGet and >> MultiValuedPut interfaces to honor the Get/Put split concepts. Although we >> don't really need the MultiValuedPut, we can have that for consistency. >> >> Let me know your thoughts on this. >> >> Regards >> Dipanjan >> >> >> >> >> >> >> >> >> >> On Wed, Feb 26, 2014 at 7:12 PM, Matt Benson <gudnabr...@gmail.com>wrote: >> >>> Don't forget about the Get/Put/split map concepts from Collections 4. It >>> would seem you could implement those interfaces and provide that amount >>> of >>> abstraction anyway. >>> >>> Matt >>> On Feb 26, 2014 3:26 AM, "Dipanjan Laha" <dipanja...@gmail.com> wrote: >>> >>> > Hi Thomas, >>> > >>> > This sounds great. Moving MultiKeyMap to the new package does sound >>> like >>> > the way to go ahead. I will start with the implementation of the >>> interface >>> > and the MultiValuedHashMap. I should be able to submit a patch with a >>> basic >>> > implementation and some test cases by the end of this week. I can then >>> > modify and incorporate changes as per your review and suggestions. >>> > >>> > Regards >>> > Dipanjan >>> > >>> > >>> > On Wed, Feb 26, 2014 at 2:32 PM, Thomas Neidhart >>> > <thomas.neidh...@gmail.com>wrote: >>> > >>> > > Hi Dipanjan, >>> > > >>> > > I was thinking about a name for the new interface, but I actually >>> like >>> > your >>> > > proposal of MultiValuedMap. >>> > > >>> > > For the package, I think we can stick with multimap, and at some >>> point we >>> > > could also move the MultiKeyMap there, which would be logical imho. >>> > > >>> > > The implementation names are also sound. >>> > > >>> > > Thomas >>> > > >>> > > >>> > > >>> > > >>> > > On Wed, Feb 26, 2014 at 9:28 AM, Dipanjan Laha <dipanja...@gmail.com >>> > >>> > > wrote: >>> > > >>> > > > Hi Thomas, >>> > > > >>> > > > It would be great if we can start the discussion on the new >>> interface >>> > for >>> > > > MultiMap and a new package for the implementations as suggested by >>> you. >>> > > > Then I'll be able to put some code together for the same. >>> > > > >>> > > > IMO we can have >>> > > > >>> > > > 1. New Interface for MultiMap with the name MultiValuedMap or >>> > MultiValMap >>> > > > (as MultiValueMap is already the existing implementing class). >>> > > > 2. New package for the implementations: >>> > > > org.apache.commons.collections.multimap or >>> > > > org.apache.commons.collections.multivaluedmap >>> > > > 3. Implementation names like : MultiValuedHashMap, >>> MultiValuedTreeMap >>> > etc >>> > > > >>> > > > Please let me know of your thoughts on these. >>> > > > >>> > > > Regards >>> > > > Dipanjan >>> > > > >>> > > > On Sun, Feb 23, 2014 at 8:36 PM, Dipanjan Laha < >>> dipanja...@gmail.com> >>> > > > wrote: >>> > > > >>> > > > > Hi Thomas, >>> > > > > >>> > > > > Thanks for your feedback. I created an improvement request in >>> Jira >>> > for >>> > > > the >>> > > > > same (https://issues.apache.org/jira/browse/COLLECTIONS-508 ) >>> as I >>> > > > > thought it could be better tracked there. Sorry for the >>> duplication >>> > in >>> > > > the >>> > > > > mail list and Jira. I have also attached a patch in Jira where I >>> have >>> > > > > modified the existing MultiMap interface and the MultiValueMap >>> > > > > implementation and their test cases. I agree that it would break >>> > > backward >>> > > > > compatibility and we should go with your suggestion of >>> deprecating >>> > the >>> > > > > existing ones and design fresh interfaces for the same. The >>> patch is >>> > > > just a >>> > > > > sample implementation to demonstrate the issue and is far from >>> being >>> > > > > complete in terms of documentation and test cases. I am also >>> > attaching >>> > > > the >>> > > > > patch here for your reference. >>> > > > > >>> > > > > Please go through the patch and also let me know of your >>> thoughts on >>> > > how >>> > > > > we should proceed with the new interface and package structure. >>> I'll >>> > be >>> > > > > happy to change and redirect the implementation as per your >>> > > suggestion. I >>> > > > > am new to Apache Commons, but with some guidance I should not >>> have >>> > > issues >>> > > > > implementing them to start with. >>> > > > > >>> > > > > As for MultiTrie, as you mentioned, we can start with it once >>> the new >>> > > > > MultiMap has been finalized. >>> > > > > >>> > > > > Regards >>> > > > > Dipanjan >>> > > > > >>> > > > > >>> > > > > >>> > > > > >>> > > > > On Sun, Feb 23, 2014 at 6:09 PM, Thomas Neidhart < >>> > > > > thomas.neidh...@gmail.com> wrote: >>> > > > > >>> > > > >> On 02/22/2014 02:00 PM, Dipanjan Laha wrote: >>> > > > >> > Hello, >>> > > > >> >>> > > > >> Hi Dipanjan, >>> > > > >> >>> > > > >> > Recently I had the need of using a MultiMap in one of my >>> > projects. I >>> > > > >> found >>> > > > >> > that commons collection already has a MultiMap interface and >>> an >>> > > > >> > implementation. >>> > > > >> > >>> > > > >> > While using the same, I found that the MultiMap interface has >>> > > methods >>> > > > >> that >>> > > > >> > are not strongly typed even though the interface supports >>> > generics. >>> > > > For >>> > > > >> > example if I have a MultiMap like so >>> > > > >> > >>> > > > >> > MultiMap<String, User> multiMap = new MultiValueMap<String, >>> > User>(); >>> > > > >> > >>> > > > >> > where User is a custom Class, then the get(key) method would >>> > return >>> > > > me >>> > > > >> an >>> > > > >> > Object which I would need to cast to a Collection like so >>> > > > >> > >>> > > > >> > Collection<User> userCol = (Collection<User>) >>> multiMap.get(key); >>> > > > >> > >>> > > > >> > I understand that this limitation comes from that fact that >>> the >>> > > > MultiMap >>> > > > >> > extends IterableMap which in turn extends Map and other >>> > interfaces. >>> > > > >> Hence >>> > > > >> > the MultiMap cannot have a get method which returns a >>> Collection >>> > > > >> instead of >>> > > > >> > Object as that would mean extending IterableMap with the >>> Generics >>> > > set >>> > > > >> to be >>> > > > >> > <K,Collection<V>>. In that case the put method's signature >>> would >>> > > > become >>> > > > >> > >>> > > > >> > public Collection<V> put(K key, Collection<V> value); >>> > > > >> > >>> > > > >> > which we do not want.The same problem would arise with other >>> > methods >>> > > > as >>> > > > >> > well, ex: containsValue method. >>> > > > >> > >>> > > > >> > My proposal is why carry on the signatures of a Map and put >>> it on >>> > > > >> MultiMap. >>> > > > >> > Where as I do agree that it is a Map after all and has very >>> > similar >>> > > > >> > implementation and functionality, it is very different at >>> other >>> > > > levels. >>> > > > >> And >>> > > > >> > even though the MultiMap interface supports generics, the >>> methods >>> > > are >>> > > > >> not >>> > > > >> > strongly typed, which defeats the purpose of having generics. >>> So >>> > why >>> > > > >> can't >>> > > > >> > we have a separate set of interfaces for MultiMap which do not >>> > > extend >>> > > > >> Map. >>> > > > >> > That way we can have strongly typed methods on the MultiMap. >>> > > > >> >>> > > > >> The MultiMap interface as it is right now is flawed, and should >>> have >>> > > > >> been cleaned up prior to the 4.0 release imho (and I regretted >>> it >>> > > > >> already before your post). >>> > > > >> >>> > > > >> As you correctly pointed out, the problem comes from the fact >>> that >>> > it >>> > > > >> extends Map<K, Object> which leads to problems once generics >>> have >>> > been >>> > > > >> introduced (before it did not matter that much as you had to >>> cast >>> > > > >> anyway, as it is also documented in the javadoc). >>> > > > >> >>> > > > >> One mitigation for this was the introduction of this method to >>> > > > >> MultiValueMap, but it is clearly not enough: >>> > > > >> >>> > > > >> public Collection<V> getCollection(Object key) >>> > > > >> >>> > > > >> >>> > > > >> Unfortunately, it is not easy to fix this now after collections >>> 4.0 >>> > > has >>> > > > >> been released. We need to keep backwards compatibility, but we >>> could >>> > > do >>> > > > >> the following: >>> > > > >> >>> > > > >> * deprecate the existing interfaces/classes: >>> > > > >> - MultiMap >>> > > > >> - MultiValueMap >>> > > > >> >>> > > > >> * design a new, clean interface (by not extending Map) >>> > > > >> * add new package multimap with concrete implementations for >>> > > different >>> > > > >> types of maps (right now only hashmaps are supported) >>> > > > >> >>> > > > >> > Please let me know your thoughts on this. I can submit a >>> patch for >>> > > > these >>> > > > >> > changes based on your feedback. One more thing, I also am in >>> need >>> > > of a >>> > > > >> > MultiTrie which is currently not there. I am implementing the >>> same >>> > > by >>> > > > >> > wrapping PatriciaTrie. Now I am a bit confused here as, if I >>> make >>> > > the >>> > > > >> > MultiTrie interface on the lines of MultiMap, it would have >>> the >>> > same >>> > > > >> > limitations. In that case I was planning to have a separate >>> set of >>> > > > >> > interfaces for MultiTrie which does not extend any other >>> > interface. >>> > > > And >>> > > > >> in >>> > > > >> > case, we do change the MultiMap interface to be independent of >>> > Map, >>> > > > then >>> > > > >> > MultiTrie can extend MultiMap. Please let me know your >>> thoughts on >>> > > > this >>> > > > >> as >>> > > > >> > well as I am implementing the same for my project right now >>> and >>> > > would >>> > > > >> like >>> > > > >> > to contribute it back to the commons collection. >>> > > > >> >>> > > > >> Patches are always welcome, but we first need a decision in >>> which >>> > > > >> direction to go, see above. >>> > > > >> >>> > > > >> Regarding the MultiTrie: >>> > > > >> >>> > > > >> Indeed, it is the same problem, so it should go hand in hand >>> with >>> > the >>> > > > >> revamp of the MultiMap interface. >>> > > > >> >>> > > > >> Thomas >>> > > > >> >>> > > > >> >>> > --------------------------------------------------------------------- >>> > > > >> To unsubscribe, e-mail: 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 >
