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https://issues.apache.org/jira/browse/MATH-742?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13211077#comment-13211077
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Neil Roeth commented on MATH-742:
---------------------------------
First, thanks for continuing to respond, I do want to understand the reasoning
behind this decision and you are helping make it clear.
{quote}
We are already in trouble, because of this lack of policy, for several classes
for which "Serializable" is a supposedly innocuous feature (e.g. fields that
should be transient cannot be because no explicit serialization is implemented).
{quote}
Do you mean that if you corrected this and made them transient, you would
introduce an incompatibility with objects serialized using older versions of
the class? If not that, then could you explain?
{quote}
In the Commons project, there is a commitment that minor releases must be fully
compatible; that implies that relying on a default serialization would prevent
any change to internal structure of a class.
{quote}
I understand completely about not making changes in minor releases. Since that
commitment is for minor releases, that implies that it could be done at the
next major release, right?
{quote}
Maybe that you are not aware of the constraints imposed by "Serializable";
maybe that you don't care because in your use-case, you'll never be confronted
to the problem of a wrong serialized form. But another user's use-case might
bring him here complaining about our inconsistent support of "Serializable".
Would he be less right than you?
{quote}
"Not aware" is more likely than "don't care". I may be ignorant but I'm not
callous. :-) I understand that suddenly changing how a class is serialized
could break things for use cases other than mine and that is no less right than
mine. Another reason to restrict the change to a major version.
{quote}
It is always trivial to add "implements Serializable" to a class definition.
But it is not trivial to do the implementation in the right way; just adding
"implements Serializable" is not the right way, never. Again, it could be good
enough for some purpose, but the wish for CM to be an example of good Java
programming, is not compatible with statements such as "We know it's sloppy, so
don't use it whenever you need something that works...".
{quote}
This is the core of the issue. I can see that implementing Serializable might
require special code in some cases, but why is just adding "implements
Serializable" _never_ the right way? You provided an example of wrapper code to
do serialization for a class that is not serializable, but would you provide an
example of how to transform a class that is not serializable directly into one
that is? I.e., not with a wrapper, but by adding "implements Serializable" and
then adding the explicit serialization methods to the class itself? I would
like to see an example of "good Java programming" with regard to serialization.
{quote}
The purpose of CM is to provide robust implementations of mathematical
utilities; supporting distributed applications is a totally different game.
{quote}
In my business, we often do massive calculations that require hundreds or
thousands of cpu-hours that need to be completed overnight, so they need to be
distributed. Regardless of how robust the implementation is otherwise, if it
does not support distribution, then that alone might make it unusable.
> Please make PolynomialSplineFunction Serializable
> -------------------------------------------------
>
> Key: MATH-742
> URL: https://issues.apache.org/jira/browse/MATH-742
> Project: Commons Math
> Issue Type: Improvement
> Affects Versions: 2.2
> Reporter: Neil Roeth
> Priority: Minor
> Attachments: PolynomialSplineFunction.java
>
>
> PolynomialSplineFunction is not Serializable, while the very similar
> PolynomialFunction class in the same package is. All that needs to be done is
> to add the import:
> {{import java.io.Serializable;}}
> and change this:
> {{public class PolynomialSplineFunction implements
> DifferentiableUnivariateRealFunction}}
> to this:
> {{public class PolynomialSplineFunction implements
> DifferentiableUnivariateRealFunction, Serializable}}
> I made exactly that modification to a local copy and it serialized
> successfully. Before the change, I got serialization errors.
> Thanks.
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