Re: [Jython-dev] Subclassing a Java class imported via a custom ClassLoader: Jython is so close....

[Leo U. <leo...@ya...>]

Im thinking some more about this and think maybe the
best way to attack it is to do it via a module. 
Something along the lines of
"register_classloader.py".
What register_classloader.py will do is allow the
developer to register classloaders in the system to
allow subclassing of classloaded classes easily.

import register_classloader
register_classloader.registerClassLoader(
classloader_instance )

behind the scenes this deals with all the internal
manipulation of the runtime.  I think though that this
will require a modification to the way the system
compiles classes.  I believe the compile sequence is:
1. Check if System state has a classloader, try
getting the class from that if there.
2. Use the System classloader to get the class if
there isn't a #1.

Im thinking that to enable this a 3rd step should be
included:
3. If #2 fails check a list a of classloaders that
have been registered with the SystemState and see if
the class can be found.

The ClassLoaders in step 3 are acquired by the
register_classloader module.

I like this approach better than:
import org.python.core.Py as Py
system_state = Py.getSystemState()
system_state.setClassLoader( ..... )
....

because it allows you to have your ClassLoader work
without monkeying around with the Jython internals
directly.  It also makes it easy to deal with a
running system that uses more than 1 custom
classloader, like mine! :)  A flaw I can see is that
it may be possible that more than one registered
classloader may have the same class loaded.  This may
be a bad problem, it certainly is bad if there are
multiple versions of the Class in the system.  Im not
sure if there is a way around this, unless their is a
marker to compile this class with this specific
classloader.

Hmmm.... maybe there is a much way of dealing with
this than what Ive just outlined???

leouser










		
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