Calling JPython functions and passing parameters for Java

Andre M. Descombes adescombes at diligo.fr
Thu Nov 2 09:58:32 CET 2000


Yes the event listener pattern is nice, but what I'm looking for is just the
functions I need to use to call a python function from java, pass some
parameters to it and get a return value.

Thanks,

Andre
Randy Hudson <rgh at inmet.com> wrote in message
news:39FF44D6.8F52AEC at inmet.com...
> "Andre M. Descombes" wrote:
>
> > I have a Java application and I would like to use JPython as a scripting
> > language.
> > What I want to do is for my Java code to fire JPython "Events" that get
the
> > parameters they need to do useful things. So what I do is I create a
string
> > which contains all Python code, and then use PythonInterpreter.Exec to
> > compile it I then call each function by name:
> > PythonInterpreter.Eval("funcname(params)"). The problem is this is
extremely
> > slow, I would like to call the JPython functions directly withoug going
> > throughe the string search, unfortunately I haven't found any docs on
how to
> > do this? I would need something to get the python object of the function
and
> > then call it with some parameters.
> >
> > Any ideas on how to do this? Any help will be appreciated!
>
> The event listener pattern works well for this. In Java, you define a
listener
> interface, which declares the callback method(s) to be called when the
> interesting
> events occur, and a way of registering listener objects. (The pattern
shows up
> a lot in Java, especially in Swing: for example, look at
> java.beans.PropertyChangeListener.) Then in JPython you define the
> actual listener, and register it. For instance, a property change listener
> might look something like:
>
> ## start of script
> from java.beans import PropertyChangeListener
> from myApplication import ListenerManager
> # ListenerManager has a static method addPropertyChangeListener
>
> class MyPropertyChangeListener(PropertyChangeListener):
>   def __init__(self):
>     # blah blah blah
>   def propertyChange(self,event):
>     # method is declared in interface PropertyChangeListener as:
>     # public abstract void propertyChange( java.beans.PropertyChangeEvent
event
> )
>     print "property", event.propertyName, "is now", event.newValue
>
> ListenerManager.addPropertyChangeListener( MyPropertyChangeListener() )
> ## end of script
>
> Depending on how you exec the script, you could have the listener manager
> be part of the environment in which the script executes.
>
> -- Randy Hudson





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