jython-users

[Jython-users] Explicitly creating listeners from callables

[Michael H. <hag...@jp...>]

Hello,

Is there a way to access jython's "callable-to-listener" conversion
explicitly?

I would like to do this:

class C:
    def __init__(self):
        # ...
        b = JComboBox(actionPerformed=self.doIt)
        # ...

    def doIt(self, e):
        # ...

but it doesn't work because JComboBox (oddly) defines an
actionPerformed method.  (See

    http://aspn.activestate.com/ASPN/Mail/Message/Jython-users/541301

for more information.)

Is there a way to access jython's "callable-to-listener" conversion
explicitly?  If so, I could do

    b = JComboBox(actionListener=jython_coersion(actionPerformed=self.doIt))

which is not quite as terse as the original, but at least better than
having to define a python wrapper class to do the trick (and probably
a bit faster, too).  Ideally this would be spelled

    b = JComboBox(actionListener=ActionListener(actionPerformed=self.doIt))

but unfortunately this produces an error

    TypeError: can't instantiate interface (java.awt.event.ActionListener)

Thanks,
Michael

-- 
Michael Haggerty
JPK Instruments
hag...@jp...

Re: [Jython-users] Explicitly creating listeners from callables

[Kevin B. <kb...@ca...>]

Michael Haggerty wrote:
>
> Is there a way to access jython's "callable-to-listener" conversion
> explicitly?  

You can (cheat a lot and) actually modify the JComboBox.__dict__:

"""
adapter.py - demo how to explicitly create an adapter for a Java interface.

This adds the capability to set 'actionPerformed=callable' in a JComboBox
constructor.

Note that this hides the 'JComboBox.actionPerformed' method which
caused the trouble in the first place, but you're not supposed to do
anything with that method, so it is probably OK...

*WARNING* This is a hack - it works for Jython 2.1, but probably won't work
with future releases.
"""
from org.python.core import PyBeanEventProperty, PyBeanEvent

def addEventProperty( objectClass, addMethodName, eventName, eventClass ):
    """Add the ability to call 'method=callable' in a constructor call.
    objectClass   - class to modify
    addMethodName - objectClass method to add a listener
    eventName     - name of event listener property ('actionListener')
    eventClass    - class of event listener interface
    """
    # code stolen from PyJavaClass.addEvent
    addMethod = objectClass.getMethod( addMethodName, [eventClass] )

    # add support for assigning individual event handlers in constructor
    for eventMethod in eventClass.getMethods():
        prop = PyBeanEventProperty(
            eventName,
            eventClass,
            addMethod,
            eventMethod
            )
        objectClass.__dict__.__setitem__( prop.__name__, prop )

    # add support for assigning 'whateverListener=WhateverListenerImpl'
    event = PyBeanEvent(eventName, eventClass, addMethod);
    objectClass.__dict__.__setitem__(event.__name__, event);



# demo code
from javax.swing import JComboBox, JFrame
from java.awt.event import ActionListener
from java.awt import Dimension, BorderLayout
def showWidget( widget, name="Demo" ):
        f = JFrame( name )
        p = f.getContentPane()
        p.add( widget, BorderLayout.NORTH )
        f.setSize( 300, 300 )
        f.show()


def test():
    # allow JComboBox( actionPerformed=callable )
    addEventProperty(
        JComboBox,
        'addActionListener',
        'actionListener',
        ActionListener
        )

    def doit( event ):
        print "doit:", event

    jc = JComboBox( range( 10 ), actionPerformed=doit )
    showWidget( jc )



Cool.  :-)

kb

Re: [Jython-users] Explicitly creating listeners from callables

[Samuele P. <ped...@bl...>]

Hi. Without messing with the internals one can do:

<adapter.py>
import new

_adapt_u=0

def adapt(listenerClass, **bindings):
   global _adapt_u
   _adapt_u +=1
   return new.classobj("_%s" % _adapt_u,( listenerClass,),bindings)()

</adapter.py>

then one can do:

>>> from javax.swing import JButton,JFrame
>>> f=JFrame("exp")
>>> from java.awt.event import ActionListener
>>> def doIt(self,e): print "ok!"
...
>>> from adapter import adapt
>>> b=JButton("Ok",actionListener=adapt(ActionListener,actionPerformed=doIt))
>>> f.contentPane.add(b)
[snipped output]
>>> f.pack()
>>> f.visible=1 # click on the button
>>> ok!

regards, Samuele Pedroni.

----- Original Message ----- 
From: Kevin Butler <kb...@ca...>
To: Michael Haggerty <hag...@jp...>
Cc: <jyt...@li...>
Sent: Friday, January 18, 2002 10:34 PM
Subject: Re: [Jython-users] Explicitly creating listeners from callables


> Michael Haggerty wrote:
> >
> > Is there a way to access jython's "callable-to-listener" conversion
> > explicitly?  
> 
> You can (cheat a lot and) actually modify the JComboBox.__dict__:
> 
> """
> adapter.py - demo how to explicitly create an adapter for a Java interface.
> 
> This adds the capability to set 'actionPerformed=callable' in a JComboBox
> constructor.
> 
> Note that this hides the 'JComboBox.actionPerformed' method which
> caused the trouble in the first place, but you're not supposed to do
> anything with that method, so it is probably OK...
> 
> *WARNING* This is a hack - it works for Jython 2.1, but probably won't work
> with future releases.
> """
> from org.python.core import PyBeanEventProperty, PyBeanEvent
> 
> def addEventProperty( objectClass, addMethodName, eventName, eventClass ):
>     """Add the ability to call 'method=callable' in a constructor call.
>     objectClass   - class to modify
>     addMethodName - objectClass method to add a listener
>     eventName     - name of event listener property ('actionListener')
>     eventClass    - class of event listener interface
>     """
>     # code stolen from PyJavaClass.addEvent
>     addMethod = objectClass.getMethod( addMethodName, [eventClass] )
> 
>     # add support for assigning individual event handlers in constructor
>     for eventMethod in eventClass.getMethods():
>         prop = PyBeanEventProperty(
>             eventName,
>             eventClass,
>             addMethod,
>             eventMethod
>             )
>         objectClass.__dict__.__setitem__( prop.__name__, prop )
> 
>     # add support for assigning 'whateverListener=WhateverListenerImpl'
>     event = PyBeanEvent(eventName, eventClass, addMethod);
>     objectClass.__dict__.__setitem__(event.__name__, event);
> 
> 
> 
> # demo code
> from javax.swing import JComboBox, JFrame
> from java.awt.event import ActionListener
> from java.awt import Dimension, BorderLayout
> def showWidget( widget, name="Demo" ):
>         f = JFrame( name )
>         p = f.getContentPane()
>         p.add( widget, BorderLayout.NORTH )
>         f.setSize( 300, 300 )
>         f.show()
> 
> 
> def test():
>     # allow JComboBox( actionPerformed=callable )
>     addEventProperty(
>         JComboBox,
>         'addActionListener',
>         'actionListener',
>         ActionListener
>         )
> 
>     def doit( event ):
>         print "doit:", event
> 
>     jc = JComboBox( range( 10 ), actionPerformed=doit )
>     showWidget( jc )
> 
> 
> 
> Cool.  :-)
> 
> kb
> 
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users
> 

Re: [Jython-users] Explicitly creating listeners from callables

[Kevin B. <kb...@ca...>]

Samuele Pedroni wrote:
>
> def adapt(listenerClass, **bindings):
>    global _adapt_u
>    _adapt_u +=1
>    return new.classobj("_%s" % _adapt_u,( listenerClass,),bindings)()

[snip] 

> >>> b=JButton("Ok",actionListener=adapt(ActionListener,actionPerformed=doIt))

I like it. :-) 

Could we even go one step further, and make the __init__ method for a Java Interface
be something very like 'adapt'?  (The current __init__ behavior (throw TypeError) is not generally useful.)

This would allow a nicer syntax:

>>> b=JButton("Ok",actionListener=ActionListener( actionPerformed=doIt ))

And would facilitate anonymous classes for other non-Event uses (which I've wanted before, but
can't think of examples right now!)

kb