Yes that's what I've been thinking as well - SegmentInfos should have a segments-related API, not a List related. Whether the infos inside are kept in a Map, List, Collection or array is an implementation detail. In fact, I have a code which uses the API and could really benefit from a Map-like interface, but perhaps other code needs things ordered (which is why we can keep a TreeMap inside, or LinkedHahsMap). That's a great example to why it should have its own API.

The Lucene code usually calls SegmentInfos.info(int), but some places call get(int) (which is inherited from Vector). That's bad.

SegmentInfos is public, though it's tagged with @lucene.experimental. I think it should be tagged with @lucene.internal as there's nothing experimental about it?

I don't mind doing the refactoring. Not sure how this will affect back-compat (is it acceptable for this classs?). I've touched SegmentInfos in LUCENE-2289, so I'll wait for someone to pick it up first, so that I don't work on it in parallel.

Thanks,
Shai

On Sun, Feb 28, 2010 at 1:37 PM, Uwe Schindler <uwe@thetaphi.de> wrote:

I think this is historically. I have seen this in my big 3.0 generification patches, too. But I did not wanted to change it as Vector has other allocation schema than ArrayList. But maybe we should simply change it, itís a package-private class, right?

But in general subclassing those implementations is not the best thing you can do. In general the class should extend Object or something else and just have final field of type List<Ö>. Exposing the whole API of List to the outside is bad.

+1 to refactor this class (and donít let it extend a Collections class).

-----

Uwe Schindler

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http://www.thetaphi.de

eMail: uwe@thetaphi.de

From: Shai Erera [mailto:serera@gmail.com]
Sent: Sunday, February 28, 2010 12:33 PM
To: java-dev@lucene.apache.org
Subject: SegmentInfos extends Vector

Hi

What's the reason SegmentInfos extends Vector rather than say ArrayList? Do we need the synchronization around it which Vector provides?

Shai