[OJB-developers] One more question

[<Joa...@tp...>]

Hy,

i forgot one question:

it seems to me that OJB converts often between Exceptions (such as the
NoSuchElementException that can happen with almost every problem). A
mechanism like the cause-system introduced in J2SE 1.4 (and seen in a
similar Way in the way JDBC handles Warnings/Errors) might be a good idea.
IMHO the System from J2SE 1.4 would be ideal, but we obviously can't force
everyone to use J2SE just because debugging get's easier this way ...

The mechanism that 1.4 provides is basically that you can tell a newly
created Exception (Throwable to be exact) what it's root cause was. This
root cause (and its stack trace) is printed in addition to the normal
stacktrace, when doing a printStackTrace(). This allows you to see all
levels of a failure (high levels as in "couldn't load this object") to
mid-level ("SqlException") to low-level ("Couldn't open ip-connection to
server:port: access denied!").

I did a little Experiment and created a Bastard exception that used
reflection to utilize the cause-system when it is available and doesn't
break, when it is not. It can be compiled with 1.3 as well as with 1.4. It
provides the benefit of a more detailed StackTrace, when beeing run in 1.4
(even if it was compiled in 1.3) and doesn't change any behaviour, when
beeing run in 1.3. This is possible, 'cause I use Reflection to call the
initCause()-Method. Normally I'd call this an ugly hack and would not allow
such a thing in production code, but my reason to do it here is, that It
provides enormous advantages while debugging and only slows down the
process of throwing an exception (which only happens in Exceptional
circumstances, where performance is not normally of any importance)).

I've adapted PersistenceBrokerException locally to support this, the only
change in API is a new Constructor that allows for both a Throwable and a
String to be provided. I've tested it with 1.3 and 1.4 and both versions
work (only 1.4 getting the benefit, 'though). If noone has any objections,
I'd like to commit this (and adapt all other Exceptions to provide the same
constructor).

regards
Joachim Sauer