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- Subject: RE: std::exception Interoperability
- From: "Erik Cassel" <erik@...>
- Date: Mon, 27 Mar 2006 10:07:26 -0800
> Any time I see a catch(...), I start worrying
Agreed. If you look at the 5.1 code you'll see that Lua throws a
lua_longjmp*. Therefore, I think that Lua should only catch a lua_longjmp*
and not a "...". Any other exception thrown within luaD_rawrunprotected
should be considered a programming error.
As an alternative to my more generic patch (posted earlier), here is a very
small patch (untested) that I think addresses the (...) issue only:
#define LUAI_TRY(L,c,a) \
if ((c)->status == 0)
(c)->status = -1;
// Serious design error. Implementers are required to
// throw *only* lua_longjmp*.
// At this point we have no idea if the Lua stack has
// an error message on it, and we don't know if (c)->status
// is valid. All bets are off.
// Pick your action :-)
[mailto:firstname.lastname@example.org] On Behalf Of Greg Falcon
Sent: Friday, March 24, 2006 2:56 PM
To: Lua list
Subject: Re: std::exception Interoperability
Any time I see a catch(...), I start worrying, so I'd love to get a
look at your improvements to the exception handling.
On 3/24/06, Erik Cassel <email@example.com> wrote:
> I have patched Lua 5.1 to seamlessly work with std::exception.
> This lets me throw an std::exception-derived object from anywhere in C++
> code. Lua will catch it and translate it appropriately in
> Also, Lua uses an std::exception-derived class to throw Lua errors. This
> means I can catch errors thrown by Lua (as in lua_touserdata).
> The benefits of this approach are:
> 1) I don't have to write exception handlers in every entry point in
> code. If my code is based on std/boost then I can be confident that
> exceptions thrown by my code will be handled by Lua. I don't have to
> translate them into lua_error() calls.
> 2) It is perfectly safe for me to intercept an exception thrown by
> Since Lua now throws std::exception-derived objects I can catch and
> errors with a catch(std::exception&) clause. Moreover, if I decide *not*
> re-throw the exception, then Lua automatically pops the error message from
> the stack.
> Has anybody else done something like this? Would it be useful to anybody?
> Have I missed something?
> I'd be happy to post my patch (and go over implementation details) and/or
> show some sample code of how it can be used.