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Kay Kay commented on SOLR-912: ------------------------------ The interface is mostly used as a proof of concept that the new class - ModernNamedList implements the same methods as that of NamedList. Eventually - the interface would be gotten rid of , once we are happy with the same. As far as NamedList , I believe if we want to have the flexibility of allowing any type in it - we might as well define it to an Object. If we do qualify it as a specific type - then we might as well implement type-safety in the class. javac does not complain today because the compiler switch to indicate type-safety errors has been turned off. Previous implementation used to be having a pre-jdk5 List , with members being String and a type depending on the index. The revised implementation has Map.Entry<String, T> interface - which is directly intuitive to what is required ( a Map with order being preserved , allowing duplicates and nulls ). I did profile with 2 different implementations , involving Map.Entry<?> and a heterogenous list with String and a type (with insertion / deletion of 100,000 records). The current implementation in fact , failed in the performance comparison in both insertion / deletion in the middle of the List ( remove () ) , since we have to add/remove elements twice from the List (as in the current impl) , as compared to 1 insertion/deletion in the Map.Entry<> implementation. ) Given that addition/deletion in the List is worst-case linear - I believe the perceived performance degradation due to additional object , turns out to be not so bad when compared to 2-path insertion / deletion as we have today. NamedList does seem to implement the interface Iterable<T> . I am not sure how the consumer of the API can have independent iterators (since only NamedList is supposed to be aware of the internal data structures and not the consumer). So I believe it would be upto NamedList<T> to provide an iterator to the user of the API. > org.apache.solr.common.util.NamedList - Typesafe efficient variant - > ModernNamedList introduced - implementing the same API as NamedList > ---------------------------------------------------------------------------------------------------------------------------------------- > > Key: SOLR-912 > URL: https://issues.apache.org/jira/browse/SOLR-912 > Project: Solr > Issue Type: Improvement > Components: clients - java > Affects Versions: 1.4 > Environment: Tomcat 6, JRE 6, Solr 1.3+ nightlies > Reporter: Kay Kay > Priority: Minor > Fix For: 1.3.1 > > Attachments: SOLR-912.patch > > Original Estimate: 72h > Remaining Estimate: 72h > > The implementation of NamedList - while being fast - is not necessarily > type-safe. I have implemented an additional implementation of the same - > ModernNamedList (a type-safe variation providing the same interface as > NamedList) - while preserving the semantics in terms of ordering of elements > and allowing null elements for key and values (keys are always Strings , > while values correspond to generics ). -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.