Java exceptions can't be rescued with "rescue Exception"
--------------------------------------------------------
Key: JRUBY-4677
URL: http://jira.codehaus.org/browse/JRUBY-4677
Project: JRuby
Issue Type: Bug
Components: Java Integration
Affects Versions: JRuby 1.4
Reporter: Charles Oliver Nutter
Fix For: JRuby 1.5
You can rescue Java exceptions like you would Ruby exceptions:
{noformat}
~/projects/jruby ➔ jruby -rjava -e "begin; raise
java.lang.NullPointerException.new; rescue java.lang.NullPointerException; puts
'rescued'; end"
rescued
{noformat}
And you can rescue exceptions that come out of Java code, which get wrapped in
a NativeException Ruby object:
{noformat}
~/projects/jruby ➔ jruby -rjava -e "begin; raise
java.lang.System.get_property(nil); rescue Exception => e; puts 'rescued: ' +
e.class.to_s; end"
rescued: NativeException
{noformat}
So there's some duality here; we don't wrap all Java exception, and have wanted
to move away from wrapping *any* Java exceptions if possible while unifying
exception handling. So the problem is that non-wrapped Java exceptions don't
extend Ruby's Exception, and so rescue Exception won't pick them up without
some special handling:
{noformat}
~/projects/jruby ➔ jruby -rjava -e "p
java.lang.NullPointerException.ancestors"[Java::JavaLang::NullPointerException,
Java::JavaLang::RuntimeException, Java::JavaLang::Exception,
Java::JavaLang::Throwable, Java::JavaIo::Serializable, Java::JavaLang::Object,
ConcreteJavaProxy, JavaProxy, JavaProxyMethods, Object, Kernel]
{noformat}
So I see a few options:
1. Make rescue Exception rescue Java Throwable as well. This will be tricky,
because we don't want to intercept exceptions we use for flow-control, but we
already special-case them anyway. It's also a little problematic to me because
you'll rescue Exception but get something that's not an Exception.
2. Try some type trickery and make all Java exceptions extend Ruby Exception in
some way. I'm not sure how this would work, and it would certainly change how
they appear to Ruby code.
3. Require that people attempting to rescue everything rescue Object, which
would pick up Java exceptions. This seems like the least desirable, since only
in JRuby would you have to do that.
--
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators:
http://jira.codehaus.org/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
---------------------------------------------------------------------
To unsubscribe from this list, please visit:
http://xircles.codehaus.org/manage_email
