Re: Lua error handling and C++

[Glenn Maynard <glenn@...>]

On Mon, Oct 16, 2006 at 12:14:53PM -0700, Sam Roberts wrote:
> On Mon, Oct 16, 2006 at 02:49:25PM -0400, Glenn Maynard wrote:
> > On Mon, Oct 16, 2006 at 11:31:28AM -0700, Sam Roberts wrote:
> > > Can't the C++ code catch all exceptions, and re-raise with lua_error()?
> > 
> > The problem is that C++ exceptions bloat executables too much to be
> > practical to leave enabled in many cases.  The use of a 150k library
> > requiring enabling an option that would bloat my binary by over 1MB
> > means it's effectively a 1.15MB library.
> 
> Then I lost the thread. If you aren't using exceptions, what is the
> C++-specific problem you have encountered?

Lua error handling, currently, depends on either using longjmp or C++
exceptions.

longjmp is incompatible with C++ destructors, and will result in leaks.
That's why Lua allows C++ exceptions to be used instead.

But I find C++ exceptions are rarely an option: on large code, they
bloat the code massively, and if you're writing small code for a small
arch, then you can't afford the smaller bloat, either.  (I ported to
a 32MB arch, and disabling exceptions won me that 1MB, which was
enormous.)

int mybinding(lua_State *L)
{
    std::string s1 = luaL_checkstring(L, 1);
    std::string s2 = luaL_checkstring(L, 2);
    ...
}

works fine, unless the second arg throws an error, in which case you'll
probably leak s1.  (This one's easy to sidestep; as binding become
less trivial, it becomes harder.)

So, I'm asking for other options.  (Not with a great deal of hope, but
maybe someone's thought of something I havn't ...)

-- 
Glenn Maynard