Re: [Py4j-users] Using copy.deepcopy() with Java Objects

[Nicolò P. <nic...@us...>]

Hi,
actually what I am trying to do is a software transactional memory library in Python able to add transactional support to Java programs.
To simplify let's say that I would like to call a commit() operation in the Java program (for example a commit for each object) that call a Python routine that get the object from Python and store it safely, meaning that changes to the object in the Java-side don't reflect the effects in the object stored in the Python-side. Then I could call a restore() operation in the Java object, that take last saved object in the Python-side and replace the current instance of the Java object.

I know it is a bit writhed or maybe useless, but it is just an experiment.

bye

Nicolò Perino
______
PhD Student @ USI - Faculty of Informatics
http://www.people.usi.ch/perinon/

On 16 Mar 2011, at 12:04, Barthelemy Dagenais wrote:

> Hi Nicolò,
> 
> as Alex says, it is not possible to use deepcopy with a Java object in 
> Python and I'm not sure it makes sense anyway. Are you trying to 
> dynamically duplicate a Java object graph from Python or...?
> 
> With more information about what you are trying to do, we may be able to 
> find an alternative.
> 
> Barthélémy
> 
> On 03/16/2011 06:50 AM, Alex Grönholm wrote:
>> 16.03.2011 12:24, Nicolò Perino kirjoitti:
>>> Hi,
>>> I was experimenting with your library P4JS and I was wandering how to create a copy of a Java object in Python environment. So I tried with the Python copy module, starting from your "stack" example:
>>> 
>>>>>> stack = gateway.entry_point.getStack()
>>>>>> stack
>>> JavaObject id=o0
>>>>>> import copy
>>>>>> a = copy.deepcopy(stack)
>>> Traceback (most recent call last):
>>>    File "<stdin>", line 1, in<module>
>>>    File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/copy.py", line 173, in deepcopy
>>>      y = copier(memo)
>>>    File "/Library/Python/2.6/site-packages/py4j/java_gateway.py", line 343, in __call__
>>>      args_command = ''.join([get_command_part(arg, self.pool) for arg in new_args])
>>>    File "/Library/Python/2.6/site-packages/py4j/protocol.py", line 208, in get_command_part
>>>      command_part = REFERENCE_TYPE + parameter._get_object_id()
>>> AttributeError: 'dict' object has no attribute '_get_object_id'
>>> 
>>> Is there a way to success in coping objects?
>> You'll have to do it on the Java side. The exact method depends on what
>> type you are trying to copy.
>>> Thank you.
>>> Bye
>>> 
>>> 
>>> Nicolò Perino
>>> ______
>>> PhD Student @ USI - Faculty of Informatics
>>> http://www.people.usi.ch/perinon/
>>> 
>>> 
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