Well didnt want to enter into this - just dont want a troll - but guava can
break apps in some cases - common enough to be taken into account - so
guava is not a solution - and i skip other drawbacks it has like its size.
Let provide a real solution since it is trivial here, no? For other cases
guava or any other implementation is great.
Le 13 mars 2015 12:13, "Eugen Cepoi" <cepoi.eugen_at_gmail.com> a écrit :
> Hey Romain,
>
> 2015-03-13 11:38 GMT+01:00 Romain Manni-Bucau <rmannibucau_at_tomitribe.com>:
>
>> Answered inline
>>
>> Le 13 mars 2015 08:28, "Inderjeet Singh" <inder_at_alumni.stanford.edu> a
>> écrit :
>> >
>> > Don't force them, but let them use the library of their choice (Guava,
>> Johnzon or any other) to create a Type object.
>> >
>>
>> This is the original issue. For advanced cases (N levels of generics with
>> N > 1) it is fine but for common cases (N =1) it sounds like a failure.
>> Said otherwise why using an api which needs another one? Just use the
>> complete one.
>>
> I understand your point but don't feel like it is a big issue. Anyway
> everyone uses guava...
>
>> > Using a constructed Type is an advanced use-case anyway. For example,
>> with Gson, a majority of use-cases get handled without constructing a type
>> ever.
>> >
>>
>> Not fully agree. List and Map are super common (just think to crud). We
>> can't rely on wrappers as for jaxb for json - just check how many people
>> get rid of jettison for alternatives cause of it. Just makes it not natural
>> so parameterized type are as common as classes for me.
>>
>
>
> I changed my mind and support the use of Type + some doc that explains to
> the users how to obtain it (with Guava probably). It looks like the easiest
> solution :) As Inder stated, if we had a TypeToken equivalent impl in std
> jdk it would be great, but as we don't...
>
> Cheers,
> Eugen
>
>>
>> > Inder
>> >
>> > On Thu, Mar 12, 2015 at 11:49 PM, Romain Manni-Bucau <
>> rmannibucau_at_gmail.com> wrote:
>> >>
>> >> We can't force a user to use a lib - or means the spec is not usable.
>> >>
>> >> Can be as simple as providing an implementation like
>> JohnzonParameterizedType [1] which is trivial but solves this issue for
>> most of cases - and several of remzining ones can be illegal (type variable
>> etc).
>> >>
>> >> [1]
>> https://git-wip-us.apache.org/repos/asf?p=incubator-johnzon.git;a=blob;f=johnzon-mapper/src/main/java/org/apache/johnzon/mapper/reflection/JohnzonParameterizedType.java;h=479268e451b88de3851dce48a97a0f6d29ca3b79;hb=dcc3a2c2a96d095251328740c03ebc0c053077c6
>> >>
>> >> - Romain
>> >>
>> >> Le 13 mars 2015 07:38, "Inderjeet Singh" <inder_at_alumni.stanford.edu>
>> a écrit :
>> >>
>> >>> My recommendation will be that this API shouldn't provide any
>> TypeLiteral.
>> >>> For the users who need that support, should use Guava in conjunction
>> with this.
>> >>>
>> >>> Inder
>> >>>
>> >>>
>> >>> On Thu, Mar 12, 2015 at 2:50 PM, Romain Manni-Bucau <
>> rmannibucau_at_tomitribe.com> wrote:
>> >>>>
>> >>>> Hi
>> >>>>
>> >>>> Type is really powerful but has one drawback: it is not working out
>> of the box. This means we need to add a reflect package with basic
>> implementations of some types in the api to make it a smooth api - at least
>> ParameterizedType and maybe a list/set/map ones cause it is very common.
>> Next issue we could hit is then we depend in the api of the jvm indirectly
>> - interfaces get new method with jvm versions sometimes so what we can do
>> is really bound to a jvm.
>> >>>>
>> >>>> That said i like the fact it avoids to introduce a new api and yet
>> another type literal but just some common helper classes.
>> >>>>
>> >>>> - Romain
>> >>>>
>> >>>> Le 12 mars 2015 18:53, "Inderjeet Singh" <inder_at_alumni.stanford.edu>
>> a écrit :
>> >>>>
>> >>>>> For Gson, we started with Type for pretty much the same reasons.
>> Also because most developers are familiar with Type, and TypeLiteral is a
>> new/advanced concept.
>> >>>>>
>> >>>>> Gson uses <T> T fromJson(String, Type) to avoid the need for
>> casting. But it is unsafe, as you point out.
>> >>>>> In practice though, I have not seen it to be a problem.
>> >>>>>
>> >>>>> TypeLiteral are very useful in JSON conversion, so we did end up
>> adding it to Gson. Once we added it, I would have liked to revise
>> fromJson() methods to use TypeLiterals instead of Type. But we couldn't do
>> that for backward compatibility reasons.
>> >>>>>
>> >>>>> So, the point really is that if TypeLiterals are going to be added
>> in a JSR, then it is better for JsonB to depend on that JSR and use
>> TypeLiterals.
>> >>>>>
>> >>>>> But if you can't depend on the TypeLiteral JSR (if any), then go
>> ahead and use Type. It works just fine.
>> >>>>>
>> >>>>> Inder
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> On Thu, Mar 12, 2015 at 9:51 AM, Eugen Cepoi <cepoi.eugen_at_gmail.com>
>> wrote:
>> >>>>>>
>> >>>>>> Hey Martin,
>> >>>>>>
>> >>>>>> 2015-03-12 17:21 GMT+01:00 Martin Vojtek <voytoo_at_gmail.com>:
>> >>>>>>>
>> >>>>>>> Hi Experts,
>> >>>>>>>
>> >>>>>>> I would like to open discussion about Generic Type Support in
>> JSON Binding.
>> >>>>>>>
>> >>>>>>> The initial proposal is to add two methods to Jsonb interface:
>> >>>>>>>
>> >>>>>>> public <T> T fromJson(String str, java.lang.reflect.Type
>> runtimeType) throws JsonbException;
>> >>>>>>>
>> >>>>>>> public String toJson(Object object, java.lang.reflect.Type
>> runtimeType) throws JsonbException;
>> >>>>>>>
>> >>>>>>> (and analogically other methods with different input/output)
>> >>>>>>>
>> >>>>>>> Based on reviewing existing options, it does not appear there is
>> a single optimal option.
>> >>>>>>>
>> >>>>>>> Reasoning behind java.lang.reflect.Type.
>> >>>>>>>
>> >>>>>>> There are several ways how to deal with generics:
>> >>>>>>>
>> >>>>>>> 1. To use java.lang.reflect.Type
>> >>>>>>> 2. Use Type Literal (e.g. GenericType ...)
>> >>>>>>> 3. Use Generic Type Builder
>> >>>>>>>
>> >>>>>>> It would be a lot of unnecessary code to build Generic Type
>> Builder. And I think this should be not part of JSON Binding.
>> >>>>>>>
>> >>>>>>
>> >>>>>> I agree with you.
>> >>>>>>
>> >>>>>>>
>> >>>>>>> Type Literal may work in some cases, but generally it doesn't
>> work (in infinite cases). It is also not backed by Java Language
>> Specification and may not work in the future. For example, Type Literal
>> doesn't work when used with lambdas or with some JVM languages different
>> than Java.
>> >>>>>>
>> >>>>>>
>> >>>>>> I understand but I think that it works in most use cases where it
>> is needed. People use it to just deal with basic generics (custom or std
>> types).
>> >>>>>>
>> >>>>>>>
>> >>>>>>> I don't want to introduce yet another GenericType class and to
>> duplicate code with some other specifications.
>> >>>>>>
>> >>>>>>
>> >>>>>> I agree it is ugly :( would have been better if there was a
>> similar thing as TypeToken from guava in std java (even if it is a hack in
>> some way).
>> >>>>>>
>> >>>>>>>
>> >>>>>>>
>> >>>>>>> Use of java.lang.reflect.Type seems like the best choice from bad
>> choices available. Integration with JAX-RS will be flawless, it is upon the
>> user to build java.lang.reflect.Type (hopefully with the help of JSON
>> Binding implementation).
>> >>>>>>>
>> >>>>>>> User can use already available Type Literal classes available in
>> the Java ecosystem.
>> >>>>>>
>> >>>>>>
>> >>>>>> Good point and most people already use guava. Only downside will
>> be the untyped result of the fromJson.
>> >>>>>> Here we can avoid user cast by doing : <T> T fromJson(String,
>> Type), but it is definitely unsafe.
>> >>>>>>
>> >>>>>> Might be interesting to have Inderjeets feedback on how it was
>> when they were using type and TypeToken.
>> >>>>>>
>> >>>>>>>
>> >>>>>>>
>> >>>>>>> Examples and pdf proposal are available at
>> >>>>>>>
>> >>>>>>>
>> https://java.net/projects/jsonb-spec/sources/git/content/spec/spec.pdf?rev=da7db533076856699cec49a4eebd300b9f4a7230
>> >>>>>>>
>> >>>>>>>
>> https://github.com/json-binding/spec/blob/default_mapping/examples/runtime/src/main/java/examples/mapping/DefaultMappingGenerics.java
>> >>>>>>>
>> >>>>>>> Looking forward to your feedback.
>> >>>>>>>
>> >>>>>>> MartinV
>> >>>>>>
>> >>>>>>
>> >>>>>
>> >>>
>> >
>>
>
>