Re: [Jython-users] Import Python class from Java

[Julian K. <jul...@gm...>]

Thx Jim

Looks like a very interesting project. Gonna keep my eye on it. :-)

Regards

On 10 September 2015 at 15:42, Jim Baker <jim...@py...> wrote:

> Julian,
>
> That's probably me in the video you mention (so likely
> https://www.youtube.com/watch?v=hLm3garVQFo)
>
> In that video, I was referencing the Clamp project, which builds on new
> functionality in Jython 2.7 such that we can *precisely* generate the
> Java bytecode produced for Python classes that implement Java interfaces
> and/or extend a Java class. By doing this precise generation, we can ensure
> aspects like Java serializability, construction, and the specific naming,
> so that you can import and use in Java (or other JVM languages).
>
> So this means you would have to modify your class A such that it does the
> requisite implementation/extension. In turn, this implementation/extension
> allows Java code to import and use your Python class - it knows how to call
> your code.
>
> Clamp is demoed here, https://github.com/jimbaker/clamped, and is under
> sporadic development at https://github.com/jythontools/clamp
>
> There are other things to be done, but I see two major missing features:
>
>    - Java annotations. Python classes should be able to support Java
>    annotations on classes and methods, ideally use @-notation - so treating
>    Java annotations as if they are Python decorators. This is just an
>    extension of the precise bytecode generation I mentioned.
>    - Maven jars. Clamp currently supports using sys.path for loading
>    jars, via a jar.pth file in site-packages. (See
>    https://docs.python.org/2/library/site.html on .pth file processing.)
>    Clamp should be able to resolve Maven coordinates, as specified in your
>    package's setup.py, to get jar artifacts, install in site-packages, and
>    thereby place on sys.path. No more telling people, you need to put
>    x.y.z.jar on CLASSPATH.
>
> In my experience, Clamp works well enough, except when building jars on
> Windows, but it needs unit testing and refactoring. (The existing Clamp
> codebase is a good example of a prototype to try out ideas that proved to
> be too successful.) The metaclass approach we use, as inspired by
> SqlAlchemy, has shown itself to be a nice API and we will certainly keep.
> Other aspects are still subject to change, but I suspect any changes will
> be minor at most for users.
>
> - Jim
>
> On Thu, Sep 10, 2015 at 6:37 AM, Julian Kennedy <jul...@gm...>
> wrote:
>
>> Hi Guys
>>
>> I somehow remember seeing a recent video showing directly importing a
>> python class from java. Something along the lines of:
>>
>> import some.python.module.MyClass
>>
>> class A {
>>     // Some java code
>>
>>     MyClass a = new MyClass();
>>
>>     // More java code
>> }
>>
>> Is this correct? Or did I see wrong?
>>
>> Regards
>>
>>
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>