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Postings from July 2013
On Thu, Jul 25, 2013 at 6:13 AM, David E. Wheeler <david@justatheory.com> wrote: >> I don't know if a stack is really needed, a localizable $THROWN_PANIC >> might be enough. > > I don’t understand. What is $THROWN_PANIC? If it is an exception object, why would it not need a trace? > > I nearly always want a trace for my exception objects. The idea, for me, is such exceptions should be unexpected and reported to the developer, who will likely need the stack. by "stack" here I meant more than one active exception at the same time, possibly living in @@. I did not intend to allude to traces. $THROWN_PANIC is a placeholder for the new single thing that is not $@. > Yeah, though if we went with the nested catch, it would affect the lexical scope in which it is declared, block or function. Perhaps not file, though. why not file? >> My internal jury is still out on the question of, does it make more >> sense to deal with the last exception thrown, the first exception >> thrown, or to have a queue of them that must all be handled to resume >> normal operations. I don't think it's possible to have simultaneous >> exceptions in C++, outside of an easy-to-imagine system that might >> embed a list of complaints in a complicated exception object. > > Could be a chain, though. For example, Throwable has a previous_exception accessor, which tends to be pretty handy. or a "consume exception" operator that keeps producing them until it runs out and must be called in a loop. There would also have to be a way to inspect the current one. So just declaring some conventions around use of @@ gives everything we could possible need. Please tell more about Throwable's previous_exception accessor. I'm guessing it stashes the active exception when throwing while handling. Is there sugar for getting the first-thrown? > > Does Perl have a DEFER block? If not, should it be a part of this conversation? Perl does not have a formal DEFER block. CPAN has Scope::OnExit and a pure-perl version providing similar semantics but clunky syntax, using the reassignment of previous values to localized variables as the trigger for running a coderef. DEFER is an essential part of golang's exception handling, and therefore belongs in this conversation. gotta run late for work dlnThread Previous | Thread Next