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From Luc Maisonobe <>
Subject [math] Re: Extensibility of CM classes
Date Thu, 11 Jul 2013 19:09:52 GMT
Hi Ajo,

Le 11/07/2013 20:38, Ajo Fod a écrit :
> More classes can be used/extended if fields generally default to protected
> instead of private as it seems it does in classes in CM now.
> Case in point is in :

In fact, having protected members is often not considered a good thing.
If for example you look at checkstyle VisibilityModifier check, you will
see that its protectedAllowed property is set to false by default.

For Apache Commons Math, we have decided to not use the default value
and our setting in checkstyle.xml explicitly put protectedAllowed to
true. However, this does not mean everything should be protected by
default. It is rather a case by case decision, and we have a tendency to
prefer restricting access than opening it.: as you have noticed there
are more private than protected fields.

In many cases, including the one you mention for inverting diagonal
matrices, its seems safer to add a protected getter for the field than
putting the field itself protected. It allows read only access to
derived class which seems sufficient in this case. In some other cases,
a setter may also be added, but direct reference to the field itself is
a dangerous thing that should be looked at precisely.

best regards,

> Cheers,
> Ajo

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