On Mar 15, 4:44 am, B Smith-Mannschott <bsmith.o...@gmail.com> wrote:
> On Mon, Mar 15, 2010 at 06:50, ataggart <alex.tagg...@gmail.com> wrote:
> > Exceptions are over/mis-used in java, particularly checked exceptions
> > (runtime exceptions aren't so bad). My sense is that those places
> > where java.lang.Exception is thrown, the exception is not expected to
> > be handled by user code, or perhaps more accurately, a direct result
> > of a bug fat-fingered into the user code, e.g.:
> > user=> (+ 5 foo)
> > java.lang.Exception: Unable to resolve symbol: foo in this context
> > (NO_SOURCE_FILE:1)
>
> That's my impression too. Unfortunately it's inconsistent with Java
> convention. Java generally uses (extensions of) RuntimeException for
> such cases. Other extensions of Exception are reserved for cases you
> *are* expected to handle.
How do you expect to handle an exception thrown by the compiler? Just
take a look at this:
user=> (defmacro foo []
(try `(+ 5 bar)
(catch Exception e (println "caught ex"))))
#'user/foo
user=> (foo)
java.lang.Exception: No such var: user/bar (NO_SOURCE_FILE:4)
Again the only exceptions that can be handled by user code are in fact
RuntimeExceptions.
> The fact that Clojure frees us from the tyranny of checked exceptions
> is nice. The fact that it then turns around and uses what are
> conventionally *checked* exceptions as if they were unchecked can only
> appear sloppy from the point of view of other JVM languages calling
> Clojure code.
Give me an example please. In the case above, it actually isn't just
a raw Exception:
user=> (type *e)
clojure.lang.Compiler$CompilerException
>
> IMHO Clojure should be throwing (extensions of) RuntimeException
> unless it's just passing through an Exception originating form some
> lower-level call into the JRE.
It does.
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