Proposal: Automatic Resource Management (original) (raw)

Stephen Colebourne scolebourne at joda.org
Sat Mar 7 11:04:24 PST 2009

Joshua Bloch wrote:

On Sat, Mar 7, 2009 at 10:21 AM, Neal Gafter <neal at gafter.com> wrote:

I don't see how that solves the problem. Are you suggesting that everywhere someone handles an exception they should also check for a chain of ignored exceptions and log them? I am not suggesting this. Most people have no need to look at these exceptions. Those who do can read them by calling the getSuppressedExceptions()method.

Most of the time, there are no exceptions in closing. Sometimes there are. And of those, just a few we care about. So its a small %age. Thus, we shouldn't necessarily worry too much about it.

The proposal does allows the supressed exceptions to be checked immediately:

try (Writer w = open()) { // process } catch (IOException ex) { if (ex.getSuppressedExceptions() > 0) { // handle exceptions } }

which is pretty neat.

If people think it's worth it, the stack trace printing code could be modified to include suppressed exceptions. In many cases, that would cause suppressed exceptions to be logged automatically. But I have some misgivings about this approach: I suspect there are programs that parse stack traces. While I frown on this behavior, and the spec does not guarantee that it works, I'd hate to be responsible for breaking these programs.

When excepion causes were added, the stack traces changed. This has precedent and is a good idea (as it makes stack traces, the standard debugging tool, more useful).

Stephen

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