Re: [Jython-users] can't invoke superclass constructor

[Charlie G. <cha...@gm...>]

Hi David,

It looks like you're hitting http://jython.org/bugs/649582.
Essentially, if you attempt to create a subclass in Python of a Java
class with a protected constructor, and that Java class is a subclass
of a class with a protected constructor, you'll see this error.   Part
of the plan for the Jython release one removed is to fix some corner
cases in python-java integration like this one, but this won't be
fixed for the upcoming 2.2 release.  A simple workaround is to create
a Java class extending ControlContribution with a public constructor
and extend that new class from Python.

Hope this helps,
Charlie

On 7/13/07, David Huebel <dav...@gm...> wrote:
> Hi all,
>
> I have run into difficulty calling a superclass constructor again.
> This time I upgraded to jython 2.2rc2 and created a minimal failure
> case.  This should either make it obvious what I'm doing wrong or make
> it easy for anyone who has Eclipse to reproduce the problem.
>
> To recap:  When my constructor attempts to call the superclass
> constructor, I get an AttributeError saying that the superclass has no
> attribute '__init__'.
>
> Here is a session where I declare a minimal subclass of the abstract
> class org.eclipse.jface.action.ControlContribution, trigger the error,
> and verify that ControlContribution has a protected constructor that
> takes a single String argument.  ECLIPSE_CP is a classpath containing
> all the jars in my eclipse/plugins/ directory.  (More comments below
> the session.)
>
> -------------------------
>
> dhuebel@shal:~$ rlwrap /opt/jython2.2rc2/jython
> -Dpython.path=$PYTHONPATH:$ECLIPSE_CP
> Jython 2.2rc2 on java1.6.0
> Type "copyright", "credits" or "license" for more information.
> >>>
> from org.eclipse.jface.action import ControlContribution
>
> class ComboContributionItem2(ControlContribution):
>     def __init__(self, labelText):
>         ControlContribution.__init__(self, labelText)
>
>     def createControl(self, *args):
>          return None
>
> >>> >>> ... ... ... >>> >>> ...
> ...
> >>> con = ComboContributionItem2('hi')
> Traceback (innermost last):
>   File "<console>", line 1, in ?
>   File "<console>", line 3, in __init__
> AttributeError: class 'org.eclipse.jface.action.ControlContribution'
> has no attribute '__init__'
> >>> len(ControlContribution.getDeclaredConstructors())
> 1
> >>> ControlContribution.getDeclaredConstructors()[0]
> protected org.eclipse.jface.action.ControlContribution(java.lang.String)
> >>>
>
> -----------------------
>
> Possibly relevant:  I can directly invoke the protected constructor of
> the abstract class java.lang.Number, but I cannot directly invoke the
> constructor of ControlContribution:
>
> >>> Number.__init__(None)
> Traceback (innermost last):
>   File "<console>", line 1, in ?
> TypeError: invalid self argument to constructor
> >>> ControlContribution.__init__(None, 'hi')
> Traceback (innermost last):
>   File "<console>", line 1, in ?
> AttributeError: class 'org.eclipse.jface.action.ControlContribution'
> has no attribute '__init__'
>
> Please help me out if there's an obvious error in my code.  Otherwise,
> are there any other debugging steps I should take?
>
> Thanks,
> David
>
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