Stefano Mazzocchi wrote, On 16/06/2003 21.12:
on 6/16/03 1:20 AM Carsten Ziegeler wrote:...
Hi,
I think I found a showstopper for 2.1 :( : 2.1 is not binary compatible to 2.0.x -
...Why is this so? Well, the reason is the change from Loggable
to LogEnabled.
...I think, mostly this affects own sitemap components inheriting from the provided classes, but of course this can occur with every class where we changed from Loggable to LogEnabled.
So, the question is: do we want to have this kind of compatibility or do the users have to recompile (which works of course as we are compatible on the source level)?
Gosh, recompiling is not that big of a deal, but I'm with you that the concept sucks.
I really don't know what to say about this :-/
Well, there is a way out, but I don't know if we want to do it. It's based on - ok, I'll say that word - an AOP interceptor mechanism(hehehe a big wording for a simple concept).
Basically, we would have to use our own classloader in the ComponentManager, and make it load the class only after having it proxyed with the LogEnabled interface.
Ok, down to simpler jargon. In JDK 1.3 there is java.lang.reflect.Proxy that can create a proxy.
"
A dynamic proxy class is a class that implements a list of interfaces specified at runtime when the class is created
A proxy interface is such an interface that is implemented by a proxy class.
A proxy instance is an instance of a proxy class.
Each proxy instance has an associated invocation handler object, which implements the interface InvocationHandler.
A method invocation on a proxy instance through one of its proxy interfaces will be dispatched to the invoke method of the instance's invocation handler, passing the proxy instance, a java.lang.reflect.Method object identifying the method that was invoked, and an array of type Object containing the arguments. The invocation handler processes the encoded method invocation as appropriate and the result that it returns will be returned as the result of the method invocation on the proxy instance.
"
So we can get
LogEnabled f = (LogEnabled)
Proxy.newProxyInstance
(LogEnabled .class.getClassLoader(),
new Class[] { LogEnabled .class },
handler
);Where handler has:
Object invoke(Object proxy, Method method, Object[] args)
In this method we can recieve the LogEnabled call and make it go to the Loggable one.
I'm not saying that Proxies are the way to go, this is just an example, but the concept remains. A cool way of doing it would be with CGLib for example (http://cglib.sourceforge.net/).
Maybe a nice opportunity for Fortress to add interceptors, and for us to use Fortress? Or maybe Fortress already has it? ;-)
--
Nicola Ken Barozzi [EMAIL PROTECTED]
- verba volant, scripta manent -
(discussions get forgotten, just code remains)
---------------------------------------------------------------------