Ugo Cei wrote:
Il giorno 20/nov/04, alle 10:34, Leszek Gawron ha scritto:
I've found some neat ant task: http://serialver.sourceforge.net/serialver.html
Then go for it! I hate those warnings and was planning to remove some of them myself, like unread local variables or declared exceptions that are never thrown.
Mmmh... before putting serialVersionUID all over the place just because Eclipse barfs, shouldn't we think a bit more about what fixing this number actually means?
AFAIK, we need to specify this when a serializable class is subject to evolutions and we want to ensure that serialized instances of an old version of a class can be reloaded by a newer version of that same class. If that constant isn't present, then the JVM will compute one automatically from the class' structure.
So, if we fix these UIDs, that means that from there on we have to take great care that future versions of these classes are structure-compatible with older versions, i.e. no field renaming or deletion, and no new field whose value is set up in the constructor.
So my feeling is that this could cause more harm than good (having a serialization exception is better than some other obscure failure) furthermore considering that Cocoon is not a system where serialized objects are supposed to be long-lived. And in the hypothetical case where that would be the case, then the relevant classes, and only these ones, could have a serialVersionUID, with the appropriate warning in the javadoc about the needed compatibility of future versions.
So my advice: disable the warning in Eclipse, and that's all!
Sylvain
-- Sylvain Wallez Anyware Technologies http://www.apache.org/~sylvain http://www.anyware-tech.com { XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }
