[boost] Re: BOOST_TRY like macros: time to add them?

From: Guillaume Melquiond (guillaume.melquiond_at_[hidden])
Date: 2004-03-01 05:11:44

Le lun 01/03/2004 à 10:26, Pavel Vozenilek a écrit :
> "Daryle Walker" <darylew_at_[hidden]> wrote
> 
> > You might want to use:
> >
> >     #define BOOST_INDEXED_SET_CATCH(x)  if(true) ; else
> >
> > instead.  This way, any dangling "else" in the outside code doesn't get
> > attached to your macro by mistake.
> >
> You found real problem in current macros! For example:
> 
> if (...)
>    BOOST_TRY {
>    ...
>   } BOOST_CATCH(...) {
>      ...
>   }
> else {
>   ...
> }
> 
> would behave differently depending on
> BOOST_NO_EXCEPTIONS.
> 
> 
> Here are macros resistant to this problem:
> 
> #if !(defined BOOST_NO_EXCEPTIONS)
> #    define BOOST_TRY try
> #    define BOOST_CATCH(x) catch(x)
> #    define BOOST_RETHROW throw
> #else
> #    if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
> #        define BOOST_TRY if ("")
> #    else
> #        define BOOST_TRY if (1)
> #    endif
> #    define BOOST_CATCH(x) else
> #    define BOOST_RETHROW
> #endif
> 
> 
> /Pavel

With this new definition of the macros, it seems to me you can't use
multiple catch (a handler sequence). But I don't see any way to define
the macros such that BOOST_TRY {} BOOST_CATCH(_) {} BOOST_CATCH(_) {}
works as expected. Adding a BOOST_TRY_END would solve the problem. But
maybe someone can find a better solution without adding any macro.

Regards,

Guillaume