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Re: RE: [Jython-users] Where is this coming from
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From: Kent J. <ke...@td...> - 2004-08-18 15:37:35
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Mark,
This is a limitation of Python - you can't overload methods by parameter type the way you can in Java.
For frameUpdate and observerUpdate try this:
def frameUpdate(self, g):
# Forward to the parent class implementation
swing.JFrame.update(self, g)
def observerUpdate(self, observable, doc):
# Whatever you wanted to put into your original update() goes here
print "actionCommand="+doc
If you have a lot of classes where you need to do this (inherit from both JFrame and Observable and implement Observable.update()) you could make a mixin class that defines the update() dispatcher, the frameUpdate() forwarding method, and a default implementation of observerUpdate(). Then your Frame/Observable classes could also inherit the mixin and just override observerUpdate() to do what is needed.
HTH,
Kent
> From: Mark Stang <ma...@ma...>
> Date: 2004/08/18 Wed AM 09:16:30 EDT
> To: Kent Johnson <ke...@td...>
> CC: jyt...@li...
> Subject: Re: RE: [Jython-users] Where is this coming from
>
> Kent,
> Thanks for the ideas. I will try and implement them. However, I don't
> know how to specify "frameupdate" vs "observerupdate". I suppose I
> could try JFrame.update and Observer.update in order to call the parent
> methods. However, I would expect that Jython would do this. It
> appears that it thinks I overrode the parent JFrame update with a local
> update and then complained because the parameters don't match. I would
> think that it should be able to tell the difference between the two.
> Maybe it is a problem with Python. I should try and duplicate the
> problem in Python to see if it is a bug in Jython.
>
> I utilize the Observer Pattern all over my Java code so this is
> something that I am going to have to fix in a lot of places or come up
> with a new way to do it.
>
> Thanks!
>
> Mark
>
> On Wed, 2004-08-18 at 04:43, Kent Johnson wrote:
>
> > I would try making update() take an optional third argument. Then use the class of the second argument to figure out which call it is. Something like this:
> > import java
> > class ClientDesktop(swing.JFrame, Observer):
> > def update(self, graphicsOrObservable, doc=None):
> > if isinstance(graphicsOrObservable, java.awt.Graphics):
> > frameUpdate(self, graphicsOrObservable)
> > else:
> > observerUpdate(self, graphicsOrObservable, doc)
> >
> > I don't know if this will work but it's worth a try...
> > Kent
> >
> > >
> > > From: Mark Stang <ma...@ma...>
> > > Date: 2004/08/18 Wed AM 01:03:48 EDT
> > > To: jyt...@li...
> > > Subject: RE: [Jython-users] Where is this coming from
> > >
> > > Any ideas on how to "inform" jython? Or I have to find another way to
> > > implement it?
> > >
> > > And since I have two of them defined with different number of
> > > parameters, shouldn't it be able to tell the difference?
> > >
> > > Thanks,
> > >
> > > Mark
> > >
> > > On Tue, 2004-08-17 at 21:31, Jeff Emanuel wrote:
> > >
> > > > JFrame also defines a method named update.
> > > >
> > > > void update(Graphics g)
> > > >
> > > >
> > > > Jython can't tell the difference between you overriding JFrame.update
> > > > or implementing Observer.update. When JFrame calls update on itself,
> > > > Jython thinks that have an overridden update method with the wrong
> > > > number of arguments.
> > > >
> > > >
> > > > ________________________________
> > > >
> > > > From: jyt...@li... on behalf of Mark Stang
> > > > Sent: Tue 8/17/2004 8:12 PM
> > > > To: jyt...@li...
> > > > Subject: [Jython-users] Where is this coming from
> > > >
> > > >
> > > > Hi,
> > > > I have a python class that extends javax.swing.JFrame and java.util.Observer. As part of the Observer implementation I created a "update" method.
> > > >
> > > > class ClientDesktop(swing.JFrame, Observer):
> > > > def __init__(self, title):
> > > > swing.JFrame.__init__(self, title=title, size=(200,200))
> > > >
> > > > def update(self, observable, doc):
> > > > print "actionCommand="+doc
> > > >
> > > > When I run it:
> > > >
> > > > if __name__== "__main__":
> > > > desktop = ClientDesktop("title")
> > > > desktop.visible = 1
> > > >
> > > > I get:
> > > > Traceback (innermost last):
> > > > (no code object) at line 0
> > > > TypeError: update() takes at least 3 arguments (2 given)
> > > >
> > > > If I remove the update method it runs fine.
> > > >
> > > > Any thoughts as to where this is coming from?
> > > >
> > > > Thanks!
> > > >
> > > > Mark
> > >
> > > --
> > > Mark Stang <ma...@ma...>
> > >
> > >
> >
> >
> >
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>
> --
> Mark Stang <ma...@ma...>
>
>
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