Re: [Jython-users] Problems with deep copy and String[]

[Pierre T. <pie...@gm...>]

2011/7/22 Dünnebeil Gerhard <Ger...@ai...>

> ** **
>
> Hello everybody,****
>
> ** **
>
> being new to this list I first want to send greetings to everyone around
> here.****
>
> ** **
>
> I joined because I ran into a problem with Jython 2.5.2 that I can’t easily
> solve on my own.****
>
> ** **
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> We embedded Jython into our own application which means we do calls to
> Python code from within java.****
>
> ** **
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> Within the call we need to make a deep copy of some structures that have
> been handed over from the java side so we have to deal with java style
> variables here.****
>
> Doing this I ran into the problem that a deep copy of an array of String
> (String[]) is not working correctly.****
>
> ** **
>
> A String[] in java is represented as an array.array with a type code of
> “java.lang.string” in Jython.****
>
> The problem comes up due to the special semantics of the array.array()
> constructor which needs either a letter (new typecode) or an object as a
> template.****
>
> ** **
>
> Deepcopy now uses –straight forward—a java.lang.string object as the
> template which seems correct for me. Unfortunately the author of
> array.array() refuses to accept this kind of argument with the error message
> “array() argument 1 must be char, not str”. So deepcopy-ing a String[]
> fails.****
>
> ** **
>
> Unfortunately the String[] is hidden in a structure (HashMap) which is a
> map of options which are only partly evaluated in the code in questions,
> most simply must be ignored and passed forward.. So it’s not easy to predict
> if such an array is there and its existence can not be pinned down to just a
> few cases. So replacing deepcopy and doing an own conversion is VERY
> inconvenient at the best.****
>
> ** **
>
> Does anybody know of a clever workaround for this problem? ****
>
> ** **
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> Best regards****
>
> Gerhard****
>
> ** **
>
>
>
Yes, this is tricky. You have to use array from jarray. Here is my solution.
"source" is a String[] from the Java side. ICopyStringArray is the interface
I am using to make my code callable from Java.

Sorry to be so late.

from  main import ICopyStringArray

from java.lang import String
from jarray import array

class StringCopier(ICopyStringArray):

    def copyStringArray(self, source):
        result = []
        for string in source:
            result.append(string)
        result = array(result, String)
        return result


Look here:
http://www.prasannatech.net/2008/09/jarray-java-arrays-from-jython.html

-- 


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