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Posted to issues@commons.apache.org by "Phil Steitz (JIRA)" <ji...@apache.org> on 2010/03/06 16:50:27 UTC
[jira] Commented: (MATH-349) Dangerous code in
"PoissonDistributionImpl"
[ https://issues.apache.org/jira/browse/MATH-349?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12842271#action_12842271 ]
Phil Steitz commented on MATH-349:
----------------------------------
The reason this constructor exists is to allow users to plug in an alternative normal distribution implementation to be used in computing normal approximations. I don't see 1) as a serious issue, but I am +1 on deprecating the setters with aim to make this class immutable in 3.0. 2) is a harder problem, as there is no requirement that a NormalDistribution be clonable. I see three solutions, none of which are particularly appealing:
1) leave as is and specify in the javadoc that z is going to be modified
2) change the implementation to avoid changing the parameters of z
3) deprecate the constructor altogether
I vote for 1) + 3) - update the javadoc, but deprecate. If we get complaints before 3.0, we can reconsider; otherwise eliminate in 3.0
> Dangerous code in "PoissonDistributionImpl"
> -------------------------------------------
>
> Key: MATH-349
> URL: https://issues.apache.org/jira/browse/MATH-349
> Project: Commons Math
> Issue Type: Bug
> Reporter: Gilles
> Priority: Minor
>
> In the following excerpt from class "PoissonDistributionImpl":
> ---CUT---
> public PoissonDistributionImpl(double p, NormalDistribution z) {
> super();
> setNormal(z);
> setMean(p);
> }
> ---CUT---
> (1) Overridable methods are called within the constructor.
> (2) The reference "z" is stored and modified within the class.
> I've encountered problem (1) in several classes while working on issue 348. In those cases, in order to remove potential problems, I copied/pasted the body of the "setter" methods inside the constructor but I think that a more elegant solution would be to remove the "setters" altogether (i.e. make the classes immutable).
> Problem (2) can also create unexpected behaviour. Is it really necessary to pass the "NormalDistribution" object; can't it be always created within the class?
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