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Re: Remove "generic" multiply/divide operations from Quantity

  • From: Otávio Gonçalves de Santana < >
  • To:
  • Subject: Re: Remove "generic" multiply/divide operations from Quantity
  • Date: Thu, 16 Oct 2014 23:51:49 -0300

And considering the old method, what do avoid me to to something like
that?:

Quantity<Time> time = ...;
Quantity<Length> length = ...;
Quantity<Mass> result = (Quantity<Mass>) time.multiply(length);

On Thu, Oct 16, 2014 at 11:28 PM, Otávio Gonçalves de Santana <
>
 wrote:

>
>
> On Thu, Oct 16, 2014 at 10:03 PM, Martin Desruisseaux <
>  >
>  wrote:
>
>>  Otavio, all the JDK examples you gave below are *safe*, because:
>>
>>    - In an empty list/set/map, the type of elements (Integer, String,
>>    etc.) become irrelevant.
>>    - In asList, the relationship between input and output types is
>>    correctly expressed. The method signature:
>>
>>  <T> List<T> asList(T... a)
>>
>>  said: "*the type of elements in the list is the same than the type of
>> the given elements*", which is correct.
>>
>> By contract, UNITSOFMEASUREMENT-62 is *unsafe*. The following method
>> signature:
>>
>> <T extends Quantity<T>,R extends Quantity<R>> Quantity<R> 
>> multiply(Quantity<T> that)
>>
>>  said: "*there is no relationship between the type of this instance Q,
>> the input type T and the output type R*" (otherwise, please show me
>> where the relationship is expressed). The fact that this signature declares
>> no relationship is why the compiler accepts anything like "mass =
>> length.multiply(time)". This method signature is wrong - t*he reality is
>> not an absence of relationship. The reality is a relationship that we can
>> not express in Java.*
>>
>> That is the point, there is two different things the semantic (business
>> rule) and the Java core source.
>>
>> And about the relationship is:
>>
>> the operations in Quantity results in another quantity.
>>
>> So:
>>
>>
>>            Speed = Length.multiply(Time);
>>
>>
>>    - public interface Speed extends Quantity<Speed>
>>    - public interface Time extends Quantity<Time>
>>    - public interface Speed extends Quantity<Speed>
>>
>>
>> But I can do same think wrong like this without the implementation take
>> care:
>>
>>
>>        Mass = Length.multiply(Time);
>>
>>
>>    - Length: Quantity
>>    - Time: Quantity
>>    - Speed: Quantity
>>
>>
>> But it's the first question that I did, take care or not this operations
>> what it the goals of this JSR.
>>
>
>
>> Martin
>>
>>
>>
>> Le 17/10/14 08:44, Otávio Gonçalves de Santana a écrit :
>>
>> About the question of Martin, Yes we can do and there are in in SE api
>> such java.util.Collections
>> <http://docs.oracle.com/javase/7/docs/api/java/util/Collections.html>,
>> java.util.Arrays
>> <http://docs.oracle.com/javase/7/docs/api/java/util/Arrays.html>, etc.
>>
>>          List<Integer> intergers = Collections.emptyList();
>>         List<String> strings = Collections.emptyList();
>>
>>         java.util.Set<Integer> intergersSet = Collections.emptySet();
>>         java.util.Set<String> stringsSet = Collections.emptySet();
>>
>>         java.util.Map<String, Integer> map = Collections.emptyMap();
>>         java.util.Map<String, String> map2 = Collections.emptyMap();
>>
>>         List<Long> longs = java.util.Arrays.asList(1L, 2L, 3L);
>>         List<Integer> ints = java.util.Arrays.asList(1, 2, 4);
>>
>>
>>  I can do something like this and still the Java language :)
>>
>>
>>
>
>
> --
> Otávio Gonçalves de Santana
>
> blog:     http://otaviosantana.blogspot.com.br/
> twitter: http://twitter.com/otaviojava
> site:     *http://about.me/otaviojava ;<http://about.me/otaviojava>*
> 55 (11) 98255-3513
>
>


-- 
Otávio Gonçalves de Santana

blog:     http://otaviosantana.blogspot.com.br/
twitter: http://twitter.com/otaviojava
site:     *http://about.me/otaviojava ;<http://about.me/otaviojava>*
55 (11) 98255-3513


Re: Remove "generic" multiply/divide operations from Quantity

(continued)

Re: Remove "generic" multiply/divide operations from Quantity

Werner Keil 10/16/2014

Re: Remove "generic" multiply/divide operations from Quantity

Jean-Marie Dautelle 10/16/2014

Re: Remove "generic" multiply/divide operations from Quantity

Otávio Gonçalves de Santana 10/16/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Otávio Gonçalves de Santana 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Werner Keil 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/18/2014

Re: Remove "generic" multiply/divide operations from Quantity

Leonardo Lima 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/18/2014

Re: Remove "generic" multiply/divide operations from Quantity

Otávio Gonçalves de Santana 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Otávio Gonçalves de Santana 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Werner Keil 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Werner Keil 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/18/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/18/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/18/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/18/2014

Re: Remove "generic" multiply/divide operations from Quantity

Werner Keil 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/18/2014

Re: Remove "generic" multiply/divide operations from Quantity

Martin Desruisseaux 10/17/2014

Re: Remove "generic" multiply/divide operations from Quantity

Werner Keil 10/17/2014
 
 
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