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https://issues.apache.org/jira/browse/MAHOUT-190?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12770621#action_12770621
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Sean Owen commented on MAHOUT-190:
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How about this compromise: I think there are several instances that everyone
where everyone will agree there's no real case for extension (e.g. test cases).
There are some cases where there's a question -- there's some case for
extension.
I'll prepare a patch where the 'clear' cases are made private, and otherwise,
raw access is replaced with getters/setters. This should be a strict
improvement. We retain API openness going forward, just in a slightly more
organized way. And the non-controversial cases are 'fixed'.
> Make all instance fields private
> --------------------------------
>
> Key: MAHOUT-190
> URL: https://issues.apache.org/jira/browse/MAHOUT-190
> Project: Mahout
> Issue Type: Improvement
> Affects Versions: 0.2
> Reporter: Sean Owen
> Assignee: Sean Owen
> Priority: Minor
> Fix For: 0.3
>
>
> This one may be more controversial but is useful and interesting enough to
> discuss.
> I personally believe instance fields should always be private. I think the
> pro- and con- debate goes like this:
> Making all fields private increases encapsulation. Fields must be made
> explicitly accessible via getters and setters, which is good -- default to
> hiding, rather than exposing. Not-hiding a field amounts to committing it to
> be a part of the API, which is rarely intended. Using getters/setters allows
> read/write access to be independently controlled and even allowed -- allows
> for read-only 'fields'. Getters/setters establish an API independent from the
> representation which is a Good Thing.
> But don't getters and setters slow things down?
> Trivially. JIT compilers will easily inline one-liners. Making fields private
> more readily allows fields to be marked final, and these two factors allow
> for optimizations by (Proguard or) JIT. It could actually speed things up.
> But isn't it messy to write all those dang getters/setters?
> Not really, and not at all if you use an IDE, which I think we all should be.
> But sometimes a class needs to share representation with its subclasses.
> Yes, and it remains possible with package-private / protected getters and
> setters. This is IMHO a rare situation anyway, and, the code is far easier to
> read when fields from a parent don't magically appear, or one doesn't wonder
> about where else a field may be accessed in subclasses. I also feel like
> sometimes making a field more visible is a shortcut enabler to some bad
> design. It usually is a bad smell.
> Thoughts on this narrative. Once again I volunteer to implement the consensus.
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