Hi Andy, I have used similar extension methods for a long time. What I like especially in extension methods is that they don't require changes in Lucene.Net kernel and make further ports of Lucene.java independent from .Net structures.
+1 for a Lucene.Net extensions in contrib. Even a +1 for a "Lucene.Net.Extensions" for the core. DIGY -----Original Message----- From: Andy Pook [mailto:andy.p...@gmail.com] Sent: Friday, June 08, 2012 10:26 PM To: lucene-net-dev@lucene.apache.org Subject: Re: [Lucene.Net] [jira] [Created] (LUCENENET-469) Convert Java Iterator classes to implement IEnumerable<T> If we don't want to add IEnumerable (though it seems that IEnumerable could be added in parallel with the existing pattern) could we add a bunch of extension methods? Something like the following... {noformat} public static class LuceneExtensions { public static IEnumerable<Term> GetEnumerable(this TermEnum termEnum) { yield return termEnum.Term(); while (termEnum.Next()) yield return termEnum.Term(); } } {noformat} Then you can... {noformat} foreach(var e in myTernEnum.GetEnumerable()) { // do stuff with e } {noformat} Not as elegant as a direct implementation but gives easy enough access to foreach sematics. The second option is to realize that you don't need to explicitly implement IEnumerable. You just need a GetEnumerator method. So just add... {noformat} public IEnumerable<Term> GetEnumerator() { yield return Term(); while (Next()) yield return Term(); } {noformat} Now you get nice foreach sematics without even mentioning IEnumerable. Compiler magic is your friend :-) BTW: Dispose() is only called automatically when exiting a using block. Exiting a foreach will not. Cheers, Andy On 24 January 2012 06:37, Christopher Currens (Created) (JIRA) < j...@apache.org> wrote: > Convert Java Iterator classes to implement IEnumerable<T> > --------------------------------------------------------- > > Key: LUCENENET-469 > URL: https://issues.apache.org/jira/browse/LUCENENET-469 > Project: Lucene.Net > Issue Type: Sub-task > Components: Lucene.Net Contrib, Lucene.Net Core > Affects Versions: Lucene.Net 2.9.4, Lucene.Net 3.0.3, Lucene.Net 2.9.4g > Environment: all > Reporter: Christopher Currens > Fix For: Lucene.Net 3.0.3 > > > The Iterator pattern in Java is equivalent to IEnumerable in .NET. > Classes that were directly ported in Java using the Iterator pattern, > cannot be used with Linq or foreach blocks in .NET. > > {{Next()}} would be equivalent to .NET's {{MoveNext()}}, and in the > below case, {{Term()}} would be as .NET's {{Current}} property. In > cases as below, it will require {{TermEnum}} to become an abstract > class with {{Term}} and {{DocFreq}} properties, which would be > returned from another class or method that implemented {{IEnumerable<TermEnum>}}. > > {noformat} > public abstract class TermEnum : IDisposable > { > public abstract bool Next(); > public abstract Term Term(); > public abstract int DocFreq(); > public abstract void Close(); > public abstract void Dispose(); > } > {noformat} > > would instead look something like: > > {noformat} > public class TermFreq > { > public abstract Term { get; } > public abstract int { get; } > } > > public abstract class TermEnum : IEnumerable<TermFreq>, IDisposable > { > // ... > } > {noformat} > > Keep in mind that it is important that if the class being converted > implements {{IDisposable}}, the class that is enumerating the terms > (in this case {{TermEnum}}) should inherit from both > {{IEnumerable<T>}} *and* {{IDisposable}}. This won't be any change to > the user, as the compiler automatically calls {{IDisposable}} when used in a {{foreach}} loop. > > -- > This message is automatically generated by JIRA. > If you think it was sent incorrectly, please contact your JIRA > administrators: > https://issues.apache.org/jira/secure/ContactAdministrators!default.js > pa For more information on JIRA, see: > http://www.atlassian.com/software/jira > > > ----- Checked by AVG - www.avg.com Version: 2012.0.2177 / Virus Database: 2433/5056 - Release Date: 06/08/12
