On 07/03/2012 08:23 PM, Robert Bradshaw wrote:
On Tue, Jul 3, 2012 at 11:11 AM, Stefan Behnel<stefan...@behnel.de> wrote:
Robert Bradshaw, 03.07.2012 19:58:
On Tue, Jul 3, 2012 at 9:38 AM, Stefan Behnel wrote:
Dag Sverre Seljebotn, 03.07.2012 18:11:
On 07/03/2012 09:14 AM, Stefan Behnel wrote:
I don't know what happens if a C++ exception is not being caught, but I
guess it would simply crash the application. That's a bit more visible than
Yep.
just printing a warning when a Python exception is being ignored due to a
missing declaration. It's really unfortunate that our documentation didn't
even mention the need for this, because it's not immediately obvious that
Cython won't handle errors in "new", and testing for memory errors isn't
quite what people commonly do in their test suites.
Apart from that, I agree, users have to take care to properly declare the
API they are using.
Is there any time you do NOT want a "catch (...) {}" block? I can't see a
C++ exception propagating to Python-land doing anything useful ever.
That would have been my intuition, too.
If it's actually embedded, with the main driver in C++, one might want
it to propagate up.
But what kind of a propagation would that be? On the way out, it could
induce anything, from side effects to resource leaks to crashes, depending
on what the state of the surrounding code is. It would leave the whole
system in an unpredictable state. I cannot imagine anyone really wanting this.
So shouldn't we just make --cplus turn *all* external functions and methods
(whether C-like or C++-like) into "except +"? (Or keep except+ for manual
translation, but always have a catch(...)".
Performance overhead is the only reason I can think of to not do this,
although IIRC C++ catch blocks are only dealt with during stack unwinds and
doesn't cost anything/much (?) when they're not triggered.
"except -1" should then actually mean both; "except + except -1". So it's
more a question of just adding catch(...) *everywhere*, than making "except
+" the default.
I have no idea if there is a performance impact, but if there isn't, always
catching all exceptions sounds like a reasonable thing to do. After all, we
have no support for catching C++ exceptions on user side.
This is a bit like following every C call with "except *" (though the
performance ratios are unclear). It just seems a lot to wrap every
single line of a non-trivial C++ using function with try..catch
blocks.
But if users are correct about their declarations, we'd end up with the
same thing. I think it's worth a try.
Most C++ code (that I've ever run into) doesn't use exceptions,
because exception handling is so broken in C++ anyways.
Did you mean that most C++ code doesn't use try/except? That's true, but
my experience is that throw is used.
Dag
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