On Thu, Aug 27, 2009 at 8:10 PM, Tim Snyder<tsnyder...@gmail.com> wrote: > > Well, I can see that LazySeq does indeed catch and wrap all Exceptions > in a RuntimeException. I also think I can work around it, but I'd > like to know why this was done? > > Was it necessary given the checked vs. unchecked exception system of > Java? >
Yes. Rich > Is it because the exception generated by a lazy sequence may no longer > be within the dynamic confines of the 'try' in which it was called and > thus should be considered a runtime exception? > > Tim Snyder wrote: >> Thanks for the replies. I'll have a look at the impl. of LazySeq >> tonight and see if that helps. It sounds like it shouldn't be a >> problem to work around though. Is there somewhere I can read that >> gives an explanation or information about why this is done? >> >> On Aug 27, 9:33 am, Meikel Brandmeyer <m...@kotka.de> wrote: >> > Hi, >> > >> > On Aug 27, 5:47 am, Tim Snyder <tsnyder...@gmail.com> wrote: >> > >> > >> > >> > >> > >> > > I'm trying to understand how laziness affects exception handling. I >> > > keep finding my exceptions wrapped in RuntimeExceptions. >> > >> > > If I have code that just throws an exception, I get what I'd expect: >> > > (throw (Exception. "Plain Exception")) --> >> > > Plain Exception >> > > [thrown class java.lang.Exception] >> > >> > > On the other hand if I make the exception lazy, it is always wrapped >> > > in a RuntimeException: >> > > (lazy-seq >> > > [(throw (Exception. >> > > "NotPlainException"))]) --> >> > > java.lang.Exception: NotPlainException >> > > [Thrown class java.lang.RuntimeException] >> > >> > > This of course makes it harder to deal with the exceptions. I've >> > > looked through the stack traces but can't see any solution. Is this >> > > due to the Java difference between checked and unchecked exceptions? >> > > Is there a reasonable way to work around it? Doall has no effect. >> > >> > You can travel down the exception chain by means of .getCause. Do that >> > until you find your Exception or maybe until the cause is not a >> > RuntimeException anymore. If you didn't find something of concern >> > rethrow the original exception. Does that make sense? >> > >> > Sincerely >> > Meikel > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
