On Fri, Apr 8, 2011 at 11:18 AM, Antoine Pitrou <solipsis at
Guido van Rossum <guido at python.org> wrote: pitrou.net> wrote:
On Fri, 8 Apr 2011 10:11:34 -0700 Guido van Rossum <guido at python.org> wrote:
With apologies for not reading the PEP or this thread in full, some comments:
- I really like the syntax "except <exc> [as <var>] [if <test>]:". This addresses a pretty common use case in my experience. I don't care for the alternate proposed syntax that started this thread. I'm not sure that the 'if' subclause makes sense without the 'as' subclause, since most likely you'd want to refer to the caught exception. I note that it is more powerful than putting "if not <test>: raise" in the body of the except-clause, because it will allow subsequent except clauses to match still. I also note that it is a much "cleaner" change than (again) reorganizing the exception hierarchy, since there is no backward compatibility to consider.
My main issue with said new syntax is that it doesn't make things much easier to write.
As I explained in other messages, it also adds semantics that are not so easily emulated with the existing syntax (you'd have to repeat code or use nested try/except blocks).
Interestingly, this is one of the few (only?) .NET features that is exposed in Visual Basic but not in C#. Maybe there's something to learn from that? http://blogs.msdn.com/b/jaredpar/archive/2008/10/09/vb-catch-when-why-so-spe... Eric.