Re: Jython Caching Argv

Hi,

> It is as easy as this to run Jython (in an empty directory that I just
> created):
>
> PS here> java -cp "C:\Jython\2.7.1-sa\jython-standalone-2.7.1.jar"
org.python.util.jython

I like to use "-jar" to infer the main class:

  java -jar "C:\Jython\2.7.1-sa\jython-standalone-2.7.1.jar"

Relatedly, I wrote a Maven-based Java code launcher called jrun [1], which
makes launching Jython even easier:

  jrun org.python:jython-standalone

Finally, Deb, depending on which other dependencies you are including in
your application, you may run into trouble with jython-standalone and
duplicate classes of incompatible versions. I maintain a variant of
jython-standalone that shades its dependencies, which you can read about
here: https://github.com/scijava/jython-shaded

Regards,
Curtis

[1] https://github.com/ctrueden/jrun/

--
Curtis Rueden
LOCI software architect - https://loci.wisc.edu/software
ImageJ2 lead, Fiji maintainer - https://imagej.net/User:Rueden


On Sun, Aug 12, 2018 at 8:11 AM, Jeff Allen <[email protected]> wrote:

> Hi Deb:
>
> By CPython I mean the implementation of the Python language written in C,
> which is the one most people mean when they just say "Python".
>
> Do not put the copy of the standard library that comes with CPython on the
> path for Jython.  It may seem to work, but then bizarre things start to
> happen and no-one can help you. Jython has its own copy with many small
> adaptations, which (for you) is in the standalone JAR and need not be
> extracted.
>
> You probably don't need python.home. It is as easy as this to run Jython
> (in an empty directory that I just created):
>
> PS here> java -cp "C:\Jython\2.7.1-sa\jython-standalone-2.7.1.jar" org.python.util.jython
> Jython 2.7.1 (default:0df7adb1b397, Jun 30 2017, 19:02:43)
> [Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation)] on java1.7.0_60
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import sys, colorsys
> >>> sys.path
> ['', 'C:\\Jython\\2.7.1-sa\\Lib', 'C:\\Jython\\2.7.1-sa\\jython-standalone-2.7.1.jar\\Lib', '__classpath__', '__pyclasspath__/', 'C:\\Users\\Jeff\\.local\\lib\\jython2.7\\site-packages']
>
> I'm not sure why we have the second entry as well as the third on the path
> in this case as the library is in the JAR:
>
> >>> colorsys.__file__
> 'C:\\Jython\\2.7.1-sa\\*jython-standalone-2.7.1.jar**\\Lib\\*colorsys.py'
> >>> exit()
>
> Now, if I define python.home to a folder that contains an alternate
> library:
>
> PS here> java "-Dpython.home=..\271-sa" -cp "C:\Jython\2.7.1-sa\jython-standalone-2.7.1.jar" org.python.util.jython
> Jython 2.7.1 (default:0df7adb1b397, Jun 30 2017, 19:02:43)
> [Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation)] on java1.7.0_60
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import sys, colorsys
> >>> sys.path
> ['', 'C:\\Users\\Jeff\\Documents\\Jython\\271-sa\\Lib', 'C:\\Jython\\2.7.1-sa\\jython-standalone-2.7.1.jar\\Lib', '__classpath__', '__pyclasspath__/', 'C:\\Users\\Jeff\\.local\\lib\\jython2.7\\site-packages', 'C:\\Users\\Jeff\\Documents\\Jython\\271-sa\\Lib\\site-packages']
> >>> colorsys.__file__
> 'C:\\Users\\Jeff\\Documents\\Jython\\271-sa\\Lib\\colorsys.py'
>
> You see that Jython has looked there first and found the colorsys module.
>
> It's always worth exploring Python at the prompt first, but I'm aware you
> want to call interpreters from Java. I'm pretty sure argv is just:
>
>             PyList argv = pyInterpreter.getSystemState().argv;
>
> This will be a copy of the default you supplied, that you can manipulate
> as you wish.
>
> Jeff
>
> Jeff Allen
>
> On 12/08/2018 10:53, Debashish wrote:
>
> Sorry, I got confused by the term CPython, I guess if I have Python
> installed its already CPython that I am using :) So the first bullet in my
> reply should only read that "Indeed I set *python.home* to my local
> CPython installation". And that worked (somehow).
>
> On Sun, 12 Aug 2018 at 15:11, Debashish <[email protected]> wrote:
>
>> Hi Jeff, Adam,
>>
>> Thanks a ton for the prompt reply. Few clarifications:
>>
>>    1. The *python.home* path I gave is the *local* Python 2.7
>>    installation path. I assume you are saying this should be *CPython*
>>    home rather. I will try this after installing CPython locally.
>>    2. The problem is that I wish to deploy my code on Pivotal Cloud
>>    Foundry (PCF) where I would not be able to install anything else apart from
>>    the application JAR, no file-system access is available as since the code
>>    runs inside PCF containers, I cannot expect Python or CPython to be
>>    installed on that system.
>>    3. I tried several thing to make it work (for e.g. extracted the *Lib*
>>    folder from the JAR and added it on the classpath, also renamed the JAR to
>>    *jython.jar* and added it to classpath, supplied the Lib folder path
>>    as *python.path* as well), none of these worked. It seems if there is
>>    no way to supply the absolute path, then there is no way to make it work
>>    from within a Java JAR.
>>    4. My Python script is current 400 LOCs and will keep on growing, so
>>    I cannot possibly call its *functions* from my Java code as it would
>>    couple it to the Python code. I guess the only better option would be to
>>    port this Python code to Java.
>>    5. I am using Jython Standalone JAR 2.7.1 from Maven central. I think
>>    what you are saying is that instead of passing command line arguments
>>    (argv) to the static *initialize* method I can pass it to the
>>    *PythonInterpreter* object rather. I am not sure how, as I do not
>>    such any such method in the API. Is there a code example available?
>>
>> Thanks again for your help.
>>
>> Deb
>>
>> On Sun, 12 Aug 2018 at 03:26, Adam Burke <[email protected]> wrote:
>>
>>> Hi Deb
>>>
>>> On top of that, depending on how the script you’re calling is written,
>>> it might be useful to call one layer down instead of using I/O. Jython lets
>>> you work with python objects fairly directly from Java, and call Python
>>> functions directly as well. So if your python script has internal functions
>>> and classes, you could call straight into them.
>>>
>>> YMMV.
>>>
>>> Adam
>>>
>>> > 在 2018年8月12日，上午7:41，Jeff Allen <[email protected]> 写道：
>>> >
>>> > I don't know anything about Spring Boot, but the standalone JAR must
>>> be on your path for you to be able to refer to "PythonInterpreter" in your
>>> code. So by "not detected" I guess you mean that Jython appear not to find
>>> its library (which is in the standalone JAR). Jython guesses based on the
>>> path to the JAR it seems to be running from (that org.python.core.Py
>>> was loaded from) but telling it is safer.
>>> >
>>> > This bit struck me as odd:
>>> >
>>> > props.put("python.home", "C:\\Dev\\Python27");
>>> >
>>> > That's not the location of CPython is it? That would cause you a world
>>> of confusion.
>>> >
>>> > However, none of that addresses your question about argv (meaning
>>> sys.argv I suppose). The important observation here is that
>>> "PythonInterpreter.initialize" is a static method that sets a default argv
>>> that all interpreters will see as they are created. It makes a big
>>> difference now what version you are using. In 2.7.0, all interpreters were
>>> really the same interpreter: you got a separate namespace for your main,
>>> but the modules where all the same, in particular every interpreter shared
>>> sys. In 2.7.1, each interpreter gets its own sys, and so each module used
>>> is loaded again for each interpreter.
>>> >
>>> > I cannot say off the top of my head what the behaviour of the default
>>> argv and sys.argv is, but I'm pretty sure the interpreter you make in the
>>> next line has its own sys and the sys.argv you could set independently,
>>> although not in the constructor.
>>> >
>>> > Jeff Allen
>>> >
>>> >> On 11/08/2018 20:16, Debashish wrote:
>>> >> Hi,
>>> >>
>>> >> I am trying to call a Python Script from a Spring Boot applications.
>>> There are two issues I am facing:
>>> >> (1) The Jython Standalone JAR is not detected and I am forced to
>>> supply the local install path as "python.home" to make it work.
>>> >> (2) Once I initialize the /PythonInterpreter/ class, it seems it
>>> caches the argv I supply to it as for the subsequent invocation it uses the
>>> same argv values. I do call the close() method to do cleanup, but it
>>> doesn't help :(
>>> >>
>>> >>                 Properties preprops = System.getProperties();
>>> >> Properties props = new Properties();
>>> >>
>>> >> props.put("python.home", "C:\\Dev\\Python27");
>>> >> props.put("python.console.encoding", "UTF-8");
>>> >> props.put("python.security.respectJavaAccessibility", "false");
>>> >> props.put("python.import.site", "false");
>>> >>
>>> >> PythonInterpreter.initialize(preprops, props, arguments);
>>> >> PythonInterpreter pyInterpreter = new PythonInterpreter();
>>> >>
>>> >> try {
>>> >> resource = new ClassPathResource("mypyscript.py");
>>> >> out = new ByteArrayOutputStream();
>>> >> err = new ByteArrayOutputStream();
>>> >> pyInterpreter.setOut(out);
>>> >> pyInterpreter.setErr(err);
>>> >> pyInterpreter.execfile(resource.getInputStream());
>>> >> result[0] = out.toString(); // reading the output
>>> >> result[1] = err.toString(); // reading any error
>>> >> } catch (Exception e) {
>>> >> throw new Exception(e);
>>> >> } finally {
>>> >> try {
>>> >> if (out != null)
>>> >> out.close();
>>> >> if (err != null)
>>> >> err.close();
>>> >> pyInterpreter.close();
>>> >> } catch (IOException e) {
>>> >> e.printStackTrace();
>>> >> }
>>> >> }
>>> >>
>>> >> Please help.
>>> >>
>>> >> Thanks,
>>> >>
>>> >> Deb
>>> >>
>>> >>
>>> >> ------------------------------------------------------------
>>> ------------------
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>>> >>
>>> >>
>>> >> _______________________________________________
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>>> >> [email protected]
>>> >> https://lists.sourceforge.net/lists/listinfo/jython-users
>>> >
>>> >
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>>
>
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