> >> >> >> > URL: http://svn.apache.org/viewvc?rev=1245061&view=rev > >> >> >> > Log: > >> >> >> > Removed unneeded clone. > >> >> >> > > >> >> >> > The clone did not protect the array used, only the reference ones. > >> >> >> > JIRA: MATH-650 > >> >> >> > >> >> >> -1 > >> >> >> > >> >> >> That was the whole point of the clone - to protect the original > >> >> >> external data. > >> >> > > >> >> > Please (re-)explain what you mean by "protect". Cf. my comment on the > >> >> > JIRA page. > >> >> > >> >> See also your comment of 30/Nov/11 00:31. > >> > > >> > I know, but my latest comment overrides that one. > >> > > >> >> The arrays in FastMathLiteralArrays are private, but the access > >> >> methods are not, and returning an array allows the caller to modify > >> >> array elements. > >> > > >> > It's true, but unless I'm mistaken, it doesn't matter since in the end > >> > there > >> > is one and only one array that will be _used_ (the modified one) and > >> > having > >> > a pristine copy somewhere else will not prevent the dire consequences of > >> > using the modified one... ;-/ > >> > >> Not sure I follow that. > >> > >> Without clone, the array entries can be changed at any time. > >> > >> With clone, there are two pristine copies; neither can be changed > >> directly as they are stored in private arrays. > > > > The question is: Why calling "clone"? > > The answer is: You get a copy and you cannot change the array stored in > > "FastMathLiteralArrays". > > But that doesn't save you from the bug that consists in changing an array > > entry from within "FastMath". > > If that potential bug exists, some methods will produce erroneous values > > because they use the copy, not the pristine original array stored in > > "FastMathLiteralArrays". [After loading, the original array is never > > accessed again.] > > > > Now if you just obtain a reference to the original array (i.e. no call to > > "clone"), the bug will indeed modify it. > > But the consequences are not worse than in the above scenario: The exact > > same erroneous values will be computed. > > Not strictly true, because it's not only the FastMath class that can > corrupt the array.
Only "our" classes (in the package "o.a.c.m.util") can access (and corrupt) the arrays. > > Of course clone does not protect against bugs in FastMath; only array > entry getters can do that. Yes. That's what I said. > But that's not the point; Yes, that's the point. > since the arrays were (at your insistence) > moved out of FastMath itself, this necessarily meant exposing the > contents to some degree. > Using clone closes that potential exposure - as would using array entry > getters. "clone" provides protection against CM developers, which I deem unnecessary, since those same developers would also be able to make the "mistake" of modifying the contents "FastMathLiteralArrays". [And the same mistake could also happen if the arrays were stored inside the "FastMath" class.] Gilles --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
