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Re: Remove "generic" multiply/divide operations from Quantity
- From: Jean-Marie Dautelle <
>
- To:
- Subject: Re: Remove "generic" multiply/divide operations from Quantity
- Date: Thu, 16 Oct 2014 23:49:21 +0200
Hi Guys,
I tred to read through the emails but I failed to understand the question !!
Werner or Martin could you pose the question in simple terms that we can
all answer by yes or no.
I am in training all week but I will try to give you my opinion / response.
Cheers,
JM
On Thu, Oct 16, 2014 at 10:11 PM, Werner Keil
<
>
wrote:
>
I left that conclusion ("pruning" of some methods or at least leaving them
>
to implementations like UOMo or JScience did previously) as a possible
>
option.
>
It could be a little inconsistent as to where to apply them. If you had a
>
Quantity type at least you'd need to cast it to SEQuantity (assuming that
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type exists in an SE specific implementation) or do all of your operations
>
with SEQuantity<Q> after all. There both
>
multiply(Number) and
>
multiply(SEQuantity) or multiply(Quantity) could still exist.
>
>
I'll try to phrase a quick question to the interested parties at Eclipse
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IoT. So far they said they prefer to stay without explicit classes, their
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response also was against a
>
R multiply(Quantity<T>) because there are so many possible return types.
>
>
About Martin's question, I can only give one example, but there are at
>
least 50-70 cases in UCUM alone where asType() broke in JDK 8u20 and above.
>
POUND_FORCE was
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Unit<Force> POUND_FORCE =
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addUnit(POUND.multiply(ACCELLERATION_OF_FREEFALL).asType(Force.class));
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but had to become
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Unit<Force> POUND_FORCE = addUnit(new ProductUnit<Force>(
>
POUND.multiply(ACCELLERATION_OF_FREEFALL)));
>
>
otherwise the SE port did not compile there any more
>
>
Thanks,
>
Werner
>
>
On Thu, Oct 16, 2014 at 9:46 PM, Leonardo Lima
>
<
>
>
wrote:
>
>
> Hello all.
>
>
>
> As Werner mentioned, I "abstained" from the voting because I understand
>
> (as Otavio also pointed) that this is a more wide problem than our use
>
> cases. API design is not my forte, I'll admit, but I'm keeping up with the
>
> discussion.
>
>
>
> Still, I think it's valid that Martin (or Otavio or even I) write to
>
> OpenJDK and ask about this, specially considering that we would like to be
>
> part of the standard platform. I don't think this would bring bad
>
> impression, au contraire, it should show that we care about what we're
>
> doing specially outside our clique.
>
>
>
> In the end, I understood that:
>
>
>
> 1. What I (really) wanted can't be achieved without "exploding" the
>
> JSR to have bajilion methods. That's not feasible.
>
> 2. The convenient way to achieve somewhat what I wanted (the
>
> signature that sparked this thread) breaks Java rules of generics
>
> expectations. That's Martin's main point.
>
> 3. The best way to continue with Generics is using the <?> and then
>
> force the API user to cast.
>
> 1. But, then, why not drop it from the signature?
>
> 2. And add signature in JSR 363.1 when better support is available
>
> in the language?
>
>
>
> Regards,
>
> Leonardo.
>
>
>
> On Thu, Oct 16, 2014 at 4:42 PM, Otávio Gonçalves de Santana <
>
>
>
>
> wrote:
>
>
>
>> Martin, did you send the email?
>
>> Please go a head.
>
>> Le 17/10/14 02:54, Werner Keil a écrit :
>
>>
>
>> Do what you cannot leave, but note, unless either of the Spec Leads
>
>> (Leonardo abstained from the ballot till he gets a better idea of the
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>> subject/discussion, Jean-Marie has been silent on all of it, maybe he is
>
>> busy or has no opinion?) sanction that, it makes a bad impression of the
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>> work of the EG[?]
>
>>
>
>> I know it will make a bad impression. But frankly, if this group can not
>
>> perform a logical analysis, we deserve it.
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>>
>
>>
>
>> We try to be as democratic as possible
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>>
>
>> But main parts of my argument is about *logic*! Democracy has nothing
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>> to do in logic. Do you think that expressions like "*if A=B and B=C
>
>> then A=C*" is a matter of opinion? On which of the following points do
>
>> you disagree? (I explained those points in more details in my first
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>> today's
>
>> email):
>
>>
>
>>
>
>> 1. *LOGICAL FACT:* the "non-wildcards" proposal, when applied to the
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>> specific case of the Java language, can not be logically consistent.
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>> 2. *LOGICAL FACT:* going ahead despite the logical problem break the
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>> integrity of Java parametric type safety.
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>> 3. *OPINION:* The JSR-363 group has no authority for breaking the
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>> Java language that way.
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>>
>
>>
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>> If I'm wrong on point 1 or 2, it should take you only 5 minutes to
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>> convince me: just point to the logical flaw in the arguments of my first
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>> today's email.
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>>
>
>>
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>> Otavio changed the Dynamic Proxy version using Reflection in the SE
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>> port. And given there is no Reflection in ME 8, most of it also got
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>> applied
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>> to RI.
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>>
>
>> Do we agree that SE can use reflection, and that ME take only a subset
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>> of quantity types?
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>>
>
>>
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>> The only place you may refer to is the old JSR 275 code as there was
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>> no other QuantityFactory in the later API:
>
>>
>
>> https://kenai.com/projects/jsr-275/sources/svn-repository/content/trunk/jsr-275/src/main/java/javax/measure/quantity/QuantityFactory.java?rev=259
>
>>
>
>> Yes I was thinking about that class. It could be simplified a little bit.
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>>
>
>>
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>> It returned the interface, but that at the time was "crippled", the
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>> Quantity had no operations.
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>>
>
>> We can add the operations, no problem with that.
>
>>
>
>>
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>> And see JScience 4.x (intended as RI of JSR 275) that took Quantity
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>> and returned Quantity<?> or Quantity<Q> for all relevant operations, not Q
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>> [?]
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>>
>
>> But nobody proposed to return Q! I explicitly wrote *Quantity<?>
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>> multiply(Quantity<?>)* in my previous email! I also wrote "*the old
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>> method signature was in my opinion the best we can achieve*". Energy is
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>> a subtype of Quantity<Energy>, which is itself assignable to Quantity<?>.
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>> Consequently a Quantity<?> multiply(Quantity<?>) method can return an
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>> instance of Energy. No need for thousands of methods or methods
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>> returning Q.
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>>
>
>>
>
>> We cannot do a "diff" between all unit systems, especially US or UCUM
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>> here, but if you do that diff, you'll see all the places that asType()
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>> simply broke the code starting with SE 8u20. Also look at SE port issues,
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>> especially all
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>> https://github.com/unitsofmeasurement/unit-impl-se/issues?q=is%3Aissue+is%3Aclosed
>
>>
>
>> I found no mention of 'asType' under that link and by browsing in the
>
>> comments, but maybe I didn't looked hard enough. Anyway this is not the
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>> main issue, since we are not proposing a Quantity.asType(Class) method.
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>>
>
>>
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>> Including the problems with asType().
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>>>
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>>> I'm sure that this problem does not exist.
>
>>>
>
>>
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>> It does, see above, in the SE 8 implementation there are very few
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>> cases where asType() did not break the code and it seems the remedy could
>
>> be used to replace all existing calls.
>
>>
>
>> Then, please point me to a place where it broke the code. Is it possible
>
>> to give me something more accurate than digging in the history of the
>
>> entire project?
>
>>
>
>> Martin
>
>>
>
>>
>
>
>
--
It is not the strongest of the species that survives, nor the most
intelligent. It is the one that is most adaptable to change. - Darwin's
Origin of Species (digest)
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