Re: [Jython-users] Automatic type coercion for python dictionarie s?

[Waclawczyk J. <Jan...@ic...>]

Hello,

I try to ask again (hopefully more precisely):

INTRODUCTION.
 I'm often using jython to test my java software (my jython scripts call java methods, I' using a mix of Junit- and PyUnit-Framework).
Some weeks ago Samuele Pedroni wrote me, that there is even automatic type coercion from jython 2-dimensional lists to java 2-dimensional arrays when calling a java method from jython(see http://aspn.activestate.com/ASPN/Mail/msg/Jython-users:493058).
It means if you define in a Java class Test1 a method like the the following:
	static public void workOn2DimArr(String[][] arr) {
	// some code
	}
then you can call it in the jython script with the 2-dimensional list as argument for this method:
>>> import Test1
>>> Test1.workOn2DimArr([["jan", "hello"],["jan", "look"]])
>>>
It works also with the integers!
I think it's an example for an excellent level of jython-java integration.
I use this feature very extensively.
(By the way: I would extend the information at http://jython.sourceforge.net/docs/usejava.html with the hint, that there is automatic type coercion support also for multidimensional arrays)

QUESTION.
I think, the same level of AUTOMATIC type coercion should be possible to jy-dictionaries/Hashtables(or related Classes) (see my first mail) and jy-Lists/Vectors. 
If it is possible for List/Arrays, why not for dictionaries/Hashtables ?

Regards, Janusz


original Messages:
Date: Tue, 5 Jun 2001 13:39:04 -0400
From: D-Man <ds...@ri...>
To: "'jyt...@li...'" <jyt...@li...>
Subject: Re: [Jython-users] Automatic type coercion for python dictionaries?

On Tue, Jun 05, 2001 at 03:29:08PM +0200, Waclawczyk Janusch wrote:
| Hello,
| 
| I try to call in my jython script a java method, which expects
| Hashtable as argument. But it fails:
| 
| 	Jython 2.0 on java1.1.8 (JIT: )
| 	>>> import Test1 # it is my java test class
| 	>>> Test1.testPyToJavaHash({"key":"value"})
| 	TypeError: testPyToJavaHash(): 1st arg can't be coerced to java.util.Hashtable
| 
| Why is it not possible? (due to primitive types ? )
| It would be a nice feature ! (e.g. int -> Integer, ...)

There is a lot of automatic type coercion done by Jython.  See the
section "Calling Java Methods and Functions" at
http://jython.sourceforge.net/docs/usejava.html.  I don't think jython
does any Java<->Java coercion but it does Python<->Java coercion.

I haven't tried passing Python dictionaries or lists to a Java method
that wants an instance of a Java class yet.

-D