How do you mean, "revisit?" I think changing [lang] at this late date would
be more trouble than it's worth.
Matt
On Sep 1, 2013 1:31 PM, "James Carman" <ja...@carmanconsulting.com> wrote:
> I favor IAE, but I want to make sure we re-visit the decision made for
> [lang] when it chose to use NPE instead.
>
> On Sun, Sep 1, 2013 at 1:37 PM, Gary Gregory <garydgreg...@gmail.com>
> wrote:
> > It feels to me that this misrepresents the ideas expressed here, or at
> > least mine ;) I am neither indifferent or favor NPE. I favor IAE, so
> > does that mean I am nor "most people". If a person make these kinds of
> > statement, we might as well VOTE or argue-discuss some more...!
> >
> > Gary
> >
> > On Sep 1, 2013, at 10:46, Benedikt Ritter <brit...@apache.org> wrote:
> >
> >> Look's like most people are either indifferent or favor NPE. So, do we
> >> change this for [CSV]? The important thing is to give users an
> expressive
> >> message.
> >>
> >> Benedikt
> >>
> >>
> >>
> >> 2013/8/30 Gary Gregory <garydgreg...@gmail.com>
> >>
> >>> Surprisingly, a lot. At work, we have a lot of frameworky/plugin-type
> of
> >>> code where we run operations on collections of things and we do not
> want
> >>> "expected" errors to torpedo the whole processing flow, so we do catch
> >>> things like IAE and ISE. We do try to avoid catching Exception if we
> can
> >>> help it.
> >>>
> >>> Gary
> >>>
> >>>
> >>> On Fri, Aug 30, 2013 at 2:32 PM, Matt Benson <gudnabr...@gmail.com>
> wrote:
> >>>
> >>>> How often do you really want to catch these?
> >>>>
> >>>> Matt
> >>>>
> >>>>
> >>>> On Fri, Aug 30, 2013 at 1:20 PM, Gary Gregory <garydgreg...@gmail.com
> >>>>> wrote:
> >>>>
> >>>>> Another perspective to think about is whether you want to write code
> >>>> like:
> >>>>>
> >>>>> try {
> >>>>> // la-di-da
> >>>>> } catch (NullPointerException e) {
> >>>>> // garbage in!
> >>>>> }
> >>>>>
> >>>>> or:
> >>>>>
> >>>>> try {
> >>>>> // doo-wap-doo-wap
> >>>>> } catch (IllegalArugumentException e) {
> >>>>> // garbage in!
> >>>>> }
> >>>>>
> >>>>> Catching NPE just smells funny to me.
> >>>>>
> >>>>> Gary
> >>>>>
> >>>>>
> >>>>>
> >>>>> On Fri, Aug 30, 2013 at 1:06 PM, sebb <seb...@gmail.com> wrote:
> >>>>>
> >>>>>> The fact that NPE is documented in Bloch is quite important.
> >>>>>>
> >>>>>> Whatever we do choose, we should make sure to document all th
> reasons
> >>>>>> (pros and cons) somewhere other than just the mailing list!
> >>>>>>
> >>>>>> On 30 August 2013 17:30, Matt Benson <gudnabr...@gmail.com> wrote:
> >>>>>>> The discussion for [lang], none of whose participants have weighed
> >>> in
> >>>>>> here,
> >>>>>>> took place in late 2009 (so perhaps a little longer ago than I
> >>>> thought)
> >>>>>> and
> >>>>>>> is archived at [1]. IMO Paul B. makes some pretty compelling
> >>>> arguments
> >>>>>> in
> >>>>>>> [2].
> >>>>>>>
> >>>>>>> Matt
> >>>>>>>
> >>>>>>> [1] http://markmail.org/thread/7gw7xzrc3c3ul74c
> >>>>>>> [2] http://markmail.org/message/wmc4jh4pmhjjtxdf
> >>>>>>>
> >>>>>>>
> >>>>>>> On Fri, Aug 30, 2013 at 11:13 AM, sebb <seb...@gmail.com> wrote:
> >>>>>>>
> >>>>>>>> The JDK Javadoc says of NPE:
> >>>>>>>>
> >>>>>>>> * Applications should throw instances of this class to indicate
> >>>>>>>> * other illegal uses of the <code>null</code> object.
> >>>>>>>>
> >>>>>>>> and of IAE:
> >>>>>>>>
> >>>>>>>> * Thrown to indicate that a method has been passed an illegal or
> >>>>>>>> * inappropriate argument.
> >>>>>>>>
> >>>>>>>> That says to me that we should throw IAE here.
> >>>>>>>>
> >>>>>>>> The JDK does use NPE for parameter checks, but it also uses IAE,
> >>> for
> >>>>>>>> example:
> >>>>>>>>
> >>>>>>>> javax.management.monitor.Monitor.addObservedObject
> >>>>>>>> java.rmi.activation.ActivationDesc.ActivationDesc
> >>>>>>>> javax.management.relation.RoleList.add
> >>>>>>>> javax.imageio.metadata.IIOMetadataFormatImpl.addAttribute
> >>>>>>>>
> >>>>>>>> On 30 August 2013 16:50, Adrian Crum <
> >>>>>> adrian.c...@sandglass-software.com>
> >>>>>>>> wrote:
> >>>>>>>>> I've seen a lot of discussions on NPE versus IAE, and in the end
> >>>>> they
> >>>>>> all
> >>>>>>>>> condense down to what Matt stated here: Those who favor NPE cite
> >>>> the
> >>>>>> JDK
> >>>>>>>>> classes as a pattern to follow, and those who favor IAE say it
> >>> is
> >>>> a
> >>>>>>>> better
> >>>>>>>>> description of the problem. From my perspective, both are valid
> >>>>>>>> viewpoints,
> >>>>>>>>> and a project simply needs to choose one. In the end, the choice
> >>>> is
> >>>>>>>> neither
> >>>>>>>>> "right" nor "wrong" - it is just a choice.
> >>>>>>>>>
> >>>>>>>>> -Adrian
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> On 8/30/2013 8:07 AM, Matt Benson wrote:
> >>>>>>>>>>
> >>>>>>>>>> Let me stir the pot:
> >>>>>>>>>> At a fundamental level I agree that a required *argument*
> >>>> should
> >>>>>>>> throw
> >>>>>>>>>> an
> >>>>>>>>>> IllegalArgumentException when null is supplied. However, ISTR
> >>>> the
> >>>>>>>>>> decision
> >>>>>>>>>> to do otherwise in [lang] having been discussed on-list in the
> >>>>>>>>>> not-so-distant past, and the result of that discussion being
> >>> that
> >>>>>> NPE is
> >>>>>>>>>> usually the result in the core JDK classes. So I wouldn't
> >>>>>> characterize
> >>>>>>>>>> the
> >>>>>>>>>> situation as "[lang] *just happens* to throw NPE." Now, [lang]
> >>>> is
> >>>>>> in a
> >>>>>>>>>> slightly unique situation as its stated mission is to
> >>> complement
> >>>>> Java
> >>>>>>>> SE,
> >>>>>>>>>> so it could be argued that [lang] is under greater pressure to
> >>>>>> conform
> >>>>>>>> for
> >>>>>>>>>> that reason. But my personal preference, in light of the
> >>>> standing
> >>>>>>>>>> decision
> >>>>>>>>>> with [lang], would be for consistency throughout Commons
> >>>> components
> >>>>>>>>>> *despite* the fact that at a purely semantic level I agree with
> >>>> the
> >>>>>>>>>> arguments in favor of IllegalArgumentException.
> >>>>>>>>>>
> >>>>>>>>>> To summarize, +1 for NullPointerException from me.
> >>>>>>>>>>
> >>>>>>>>>> Matt
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> On Fri, Aug 30, 2013 at 9:36 AM, Benedikt Ritter <
> >>>>> brit...@apache.org
> >>>>>>>
> >>>>>>>>>> wrote:
> >>>>>>>>>>
> >>>>>>>>>>> 2013/8/30 sebb <seb...@gmail.com>
> >>>>>>>>>>>
> >>>>>>>>>>>> On 30 August 2013 15:19, Benedikt Ritter <brit...@apache.org
> >>>>
> >>>>>> wrote:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> I've removed the generics in r1518974, thanks for spotting
> >>>> that
> >>>>>> sebb.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Regarding the exception to throw I'm indifferent. The
> >>>> important
> >>>>>> thing
> >>>>>>>>>>>
> >>>>>>>>>>> is
> >>>>>>>>>>>>
> >>>>>>>>>>>> to
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> fail early.
> >>>>>>>>>>>> ... and with a helpful message.
> >>>>>>>>>>>>
> >>>>>>>>>>>>> I personally thing that NPE should be reserved for signaling
> >>>>> that
> >>>>>>>> some
> >>>>>>>>>>>>
> >>>>>>>>>>>> code
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> tried to invoke a method on a null reference.
> >>>>>>>>>>>>
> >>>>>>>>>>>> +1
> >>>>>>>>>>>>
> >>>>>>>>>>>>> In our case null is illegal because we know that some code
> >>>> later
> >>>>>> on
> >>>>>>>>>>>
> >>>>>>>>>>> would
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> break if we accept a null reference. So
> >>> IllegalStateException
> >>>>>> makes
> >>>>>>>>>>>>
> >>>>>>>>>>>> sense.
> >>>>>>>>>>>>
> >>>>>>>>>>>> s/IllegalStateException /IllegalArgumentException/
> >>>>>>>>>>>>
> >>>>>>>>>>>> +1
> >>>>>>>>>>> Sorry, I meant IAE of corse.
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>>> Imaging having a method that accepts an int and only
> >>> positive
> >>>>> ints
> >>>>>>>> are
> >>>>>>>>>>>>> valid. You would throw an IllegalArgumentException if a
> >>>> negative
> >>>>>> int
> >>>>>>>> is
> >>>>>>>>>>>>> passed to that method and not a NegativeIntegerException (or
> >>>>> what
> >>>>>>>>>>>
> >>>>>>>>>>> ever).
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> But James has a point. If [LANG] uses NPE maybe we should
> >>>> stick
> >>>>> to
> >>>>>>>>>>>
> >>>>>>>>>>> this.
> >>>>>>>>>>>>
> >>>>>>>>>>>> I don't think we have to do the same as LANG, so long as the
> >>>>>> Javadoc
> >>>>>>>> is
> >>>>>>>>>>>> clear.
> >>>>>>>>>>>>
> >>>>>>>>>>>>> Feel free to change it. I'll leave it for now since there
> >>>>> doesn't
> >>>>>>>> seem
> >>>>>>>>>>>
> >>>>>>>>>>> to
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> be consensus?!
> >>>>>>>>>>>>
> >>>>>>>>>>>> Unless there are other reasons than "LANG happens to use
> >>> NPE" I
> >>>>>> think
> >>>>>>>>>>>> we should stick with IAE, as it more clearly indicates the
> >>> the
> >>>>>> problem
> >>>>>>>>>>>> is not within the method throwing it.
> >>>>>>>>>>>>
> >>>>>>>>>>>> The problem with using NPE to flag parameter errors is that
> >>> it
> >>>>>>>>>>>> confuses the user as to the likely cause.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Leave NPEs to the runtime system.
> >>>>>>>>>>> agreed.
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>>> Benedikt
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> 2013/8/30 James Carman <ja...@carmanconsulting.com>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> Well, the problem with using NPE is that we as Java
> >>>> developers
> >>>>>> have
> >>>>>>>>>>>>>> learned through the years that NPE typically is an "oh
> >>> crap"
> >>>>>>>>>>>>>> situation, where something is terribly wrong (we hate
> >>> seeing
> >>>>>> those).
> >>>>>>>>>>>>>> Thus, our users may have knee-jerk reactions and not even
> >>>> know
> >>>>> to
> >>>>>>>>>>>>>> inspect the message for the real cause. IAE is less
> >>>> alarming,
> >>>>>> IMHO.
> >>>>>>>>>>>>>> Just my $0.02, but we've been doing it that way for a long
> >>>> time
> >>>>>> in
> >>>>>>>>>>>>>> [lang], so be it.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> On Fri, Aug 30, 2013 at 9:01 AM, sebb <seb...@gmail.com>
> >>>>> wrote:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> AFAIK "accidental" NPEs don't have a message associated
> >>> with
> >>>>>> them.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> So provided that the assertion generates the NPE with a
> >>>>> suitable
> >>>>>>>>>>>>>>> message (e.g.as currently done for the IAE) then it
> >>>> *should*
> >>>>> be
> >>>>>>>>>>>>>>> possible for the end user to distinguish the two cases.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> I am slightly in favour of retaining IAE as the cause is
> >>>>> obvious
> >>>>>>>>>>>
> >>>>>>>>>>> with
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> needing to look at the NPE message.
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> ==
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Horrible hack: - if you want to use NPE, you could wrap an
> >>>> IAE
> >>>>>> in
> >>>>>>>>>>>
> >>>>>>>>>>> the
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> NPE:
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> npe = new NPE(msg);
> >>>>>>>>>>>>>>> npe.initCause(new IAE(msg));
> >>>>>>>>>>>>>>> throw npe;
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Or vice-vera, of course!
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> Not sure that gains anything, but it does make the stack
> >>>> trace
> >>>>>> look
> >>>>>>>>>>>>>>> more impressive!
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> On 30 August 2013 13:42, James Carman <
> >>>>>> ja...@carmanconsulting.com>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> Commons Lang's Validate.notNull() throws NPEs. I don't
> >>>> know
> >>>>>> that
> >>>>>>>>>>>>
> >>>>>>>>>>>> I've
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> necessarily agreed with that, but at some point a
> >>> decision
> >>>>> was
> >>>>>>>> made
> >>>>>>>>>>>>>>>> that null constraint violations should throw NPEs. Food
> >>>> for
> >>>>>>>>>>>
> >>>>>>>>>>> thought.
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> On Fri, Aug 30, 2013 at 8:32 AM, Gary Gregory <
> >>>>>>>>>>>>
> >>>>>>>>>>>> garydgreg...@gmail.com>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> On Fri, Aug 30, 2013 at 8:25 AM, Emmanuel Bourg <
> >>>>>>>>>>>
> >>>>>>>>>>> ebo...@apache.org>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> wrote:
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> + if (parameter == null) {
> >>>>>>>>>>>>>>>>>>>> + throw new
> >>>>> IllegalArgumentException("Parameter
> >>>>>> '"
> >>>>>>>>>>>
> >>>>>>>>>>> +
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> parameterName + "' must not be null!");
> >>>>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>>>> + }
> >>>>>>>>>>>>>>>>>>>> + }
> >>>>>>>>>>>>>>>>>>>> +}
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Isn't a null value supposed to throw a NPE ?
> >>>>>>>>>>>>>>>>> Not always IMO. When I see an NPE I assume something is
> >>>> very
> >>>>>>>> wrong
> >>>>>>>>>>>>
> >>>>>>>>>>>> and
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> that
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> it could be a bug in the impl OR a call site, somewhere
> >>> on
> >>>>> the
> >>>>>>>>>>>
> >>>>>>>>>>> code
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> path.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> With an IAE, I know for sure it's a problem in the call
> >>>> site
> >>>>>>>>>>>
> >>>>>>>>>>> (which
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> could
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> be a bug of course).
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> I does not help that the JRE/JDK is inconsistent, so
> >>> it's
> >>>>>> hard to
> >>>>>>>>>>>>
> >>>>>>>>>>>> find
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> examples.
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> Gary
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> Emmanuel Bourg
> >>>>>>
> ---------------------------------------------------------------------
> >>>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>>> To unsubscribe, e-mail:
> >>>> dev-unsubscr...@commons.apache.org
> >>>>>>>>>>>>>>>>>> For additional commands, e-mail:
> >>>>> dev-h...@commons.apache.org
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> --
> >>>>>>>>>>>>>>>>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org
> >>>>>>>>>>>>>>>>> Java Persistence with Hibernate, Second Edition<
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> http://www.manning.com/bauer3/>
> >>>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>>> JUnit in Action, Second Edition <
> >>>>>>>> http://www.manning.com/tahchiev/
> >>>>>>>>>>>>>>>>> Spring Batch in Action <
> >>> http://www.manning.com/templier/>
> >>>>>>>>>>>>>>>>> Blog: http://garygregory.wordpress.com
> >>>>>>>>>>>>>>>>> Home: http://garygregory.com/
> >>>>>>>>>>>>>>>>> Tweet! http://twitter.com/GaryGregory
> >>>>>>
> ---------------------------------------------------------------------
> >>>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>>> To unsubscribe, e-mail:
> >>> dev-unsubscr...@commons.apache.org
> >>>>>>>>>>>>>>>> For additional commands, e-mail:
> >>>> dev-h...@commons.apache.org
> >>>>>>
> ---------------------------------------------------------------------
> >>>>>>>>>>>>>>>
> >>>>>>>>>>>>>>> To unsubscribe, e-mail:
> >>> dev-unsubscr...@commons.apache.org
> >>>>>>>>>>>>>>> For additional commands, e-mail:
> >>>> dev-h...@commons.apache.org
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> >>>>>>>>>>>>>> For additional commands, e-mail:
> >>> dev-h...@commons.apache.org
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> --
> >>>>>>>>>>>>> http://people.apache.org/~britter/
> >>>>>>>>>>>>> http://www.systemoutprintln.de/
> >>>>>>>>>>>>> http://twitter.com/BenediktRitter
> >>>>>>>>>>>>> http://github.com/britter
> >>>>>>
> ---------------------------------------------------------------------
> >>>>>>>>>>>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org
> >>>>>>>>>>>> For additional commands, e-mail: dev-h...@commons.apache.org
> >>>>>>>>>>>
> >>>>>>>>>>> --
> >>>>>>>>>>> http://people.apache.org/~britter/
> >>>>>>>>>>> http://www.systemoutprintln.de/
> >>>>>>>>>>> http://twitter.com/BenediktRitter
> >>>>>>>>>>> http://github.com/britter
> >>>>> ---------------------------------------------------------------------
> >>>>>>>>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org
> >>>>>>>>> For additional commands, e-mail: dev-h...@commons.apache.org
> >>>> ---------------------------------------------------------------------
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> >>>>>>
> >>>>>>
> ---------------------------------------------------------------------
> >>>>>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org
> >>>>>> For additional commands, e-mail: dev-h...@commons.apache.org
> >>>>>
> >>>>>
> >>>>> --
> >>>>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org
> >>>>> Java Persistence with Hibernate, Second Edition<
> >>>>> http://www.manning.com/bauer3/>
> >>>>> JUnit in Action, Second Edition <http://www.manning.com/tahchiev/>
> >>>>> Spring Batch in Action <http://www.manning.com/templier/>
> >>>>> Blog: http://garygregory.wordpress.com
> >>>>> Home: http://garygregory.com/
> >>>>> Tweet! http://twitter.com/GaryGregory
> >>>
> >>>
> >>>
> >>> --
> >>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org
> >>> Java Persistence with Hibernate, Second Edition<
> >>> http://www.manning.com/bauer3/>
> >>> JUnit in Action, Second Edition <http://www.manning.com/tahchiev/>
> >>> Spring Batch in Action <http://www.manning.com/templier/>
> >>> Blog: http://garygregory.wordpress.com
> >>> Home: http://garygregory.com/
> >>> Tweet! http://twitter.com/GaryGregory
> >>
> >>
> >>
> >> --
> >> http://people.apache.org/~britter/
> >> http://www.systemoutprintln.de/
> >> http://twitter.com/BenediktRitter
> >> http://github.com/britter
> >
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> >
>
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