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From "Laimonas Simutis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENENET-469) Convert Java Iterator classes to implement IEnumerable<T>
Date Fri, 25 Jan 2019 13:54:00 GMT

    [ https://issues.apache.org/jira/browse/LUCENENET-469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16752276#comment-16752276
] 

Laimonas Simutis commented on LUCENENET-469:
--------------------------------------------

Removing fix version of 4.8. This is a general lucene.net task and we should not delay 4.8
release.

> 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 2.9.4g, Lucene.Net 3.0.3, Lucene.Net
4.8.0
>         Environment: all
>            Reporter: Christopher Currens
>            Priority: Major
>
> 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.



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