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From "Frederick F. Kautz IV" <fka...@redhat.com>
Subject Re: Scala 2.10/2.11 Maven dependencies
Date Wed, 28 Oct 2015 18:31:18 GMT
No idea if I get a vote ;) Nevertheless, +1 to have binaries for both 
versions in Maven and explicitly "scala versioned".

Some background on this for those not as familiar with scala versioning:

It's considered best practice to label what version of scala a library 
uses in the artifact id.

The reason is compiled scala code is only compatible with the major 
version of scala it was compiled for. For example, a library compatible 
with 2.10 is not compatible with 2.11. The same will be true with 2.12 
once it is released. Mixing versions will result in undefined behavior 
which will likely manifest itself as runtime exceptions.

The convention to fix this problem is for all published libraries to 
specify the version of scala they are compatible with. Leaving out the 
scala version in a library is akin to saying "We don't depend on scala 
for this library, so feel free to use whatever you want." Sbt users will 
typically specify the version of scala they use and tooling is built 
around ensuring consistency with the "%%" operator.


scalaVersion := "2.11.4"

// this resolves to to artifactID: "scalacheck_2.11"
libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.12.0" % "test"

The most important part of this is that the scala version is explicit 
which eliminates the problem for downstream users.


On 10/28/2015 10:55 AM, Fabian Hueske wrote:
> +1 to have binaries for both versions in Maven and as build to download.
> 2015-10-26 17:11 GMT+01:00 Theodore Vasiloudis <
> theodoros.vasiloudis@gmail.com>:
>> +1 for having binaries, I'm working on a Spark application currently with
>> Scala 2.11 and having to rebuild everything when deploying e.g. to EC2 is a
>> pain.
>> On Mon, Oct 26, 2015 at 4:22 PM, Ufuk Celebi <uce@apache.org> wrote:
>>> I agree with Till, but is this something you want to address in this
>>> release already?
>>> I would postpone it to 1.0.0.
>>> – Ufuk
>>>> On 26 Oct 2015, at 16:17, Till Rohrmann <trohrmann@apache.org> wrote:
>>>> I would be in favor of deploying also Scala 2.11 artifacts to Maven
>> since
>>>> more and more people will try out Flink with Scala 2.11. Having the
>>>> dependencies in the Maven repository makes it considerably easier for
>>>> people to get their Flink jobs running.
>>>> Furthermore, I observed that people are not aware that our deployed
>>>> artifacts, e.g. flink-runtime, are built with Scala 2.10. As a
>>> consequence,
>>>> they mix flink dependencies with other dependencies pulling in Scala
>> 2.11
>>>> and then they wonder that the program crashes. It would be, imho,
>> clearer
>>>> if all our dependencies which depend on a specific Scala version would
>>> have
>>>> the corresponding Scala suffix appended.
>>>> Adding the 2.10 suffix would also spare us the hassle of upgrading to a
>>>> newer Scala version in the future, because then the artifacts wouldn't
>>>> share the same artifact name.
>>>> Cheers,
>>>> Till
>>>> On Mon, Oct 26, 2015 at 4:04 PM, Maximilian Michels <mxm@apache.org>
>>> wrote:
>>>>> Hi Flinksters,
>>>>> We have recently committed an easy way to change Flink's Scala
>> version.
>>> The
>>>>> question arises now whether we should ship Scala 2.11 as binaries and
>>> via
>>>>> Maven. For the rc0, I created all binaries twice, for Scala 2.10 and
>>> 2.11.
>>>>> However, I didn't create Maven artifacts. This follows our current
>>> shipping
>>>>> strategy where we only ship Hadoop1 and Hadoop 2.3.0 Maven
>> dependencies
>>> but
>>>>> additionally Hadoop 2.4, 2.6, 2.7 as binaries.
>>>>> Should we also upload Maven dependencies for Scala 2.11?
>>>>> If so, the next question arises: What version pattern should we have
>> for
>>>>> the Flink Scala 2.11 dependencies? For Hadoop, we append -hadoop1 to
>> the
>>>>> VERSION, e.g. artifactID=flink-core, version=0.9.1-hadoop1.
>>>>> However, it is common practice to append the suffix to the artifactID
>> of
>>>>> the Maven dependency, e.g. artifactID=flink-core_2.11, version=0.9.1.
>>> This
>>>>> has mostly historic reasons but is widely used.
>>>>> Whatever naming pattern we choose, it should be consistent. I would be
>>> in
>>>>> favor of changing our artifact names to contain the Hadoop and Scala
>>>>> version. This would also imply that all Scala dependent Maven modules
>>>>> receive a Scala suffix (also the default Scala 2.10 modules).
>>>>> Cheers,
>>>>> Max

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