----- Original Message -----
From: "David Abrahams" <dave@[...].com> 
To: "Boost mailing list" <boost@[...].org> 
Sent: Thursday, November 14, 2002 7:18 PM
Subject: Re: [boost] Proposed Boost Assert -- once again


>  "Fernando Cacciola" <fernando_cacciola@[...].com> writes:
> 
>  > ----- Original Message -----
>  > From: "Peter Dimov" <pdimov@[...].net>
>  > To: "Boost mailing list" <boost@[...].org>
>  > Sent: Thursday, November 14, 2002 1:32 PM
>  > Subject: Re: [boost] Proposed Boost Assert -- once again
>  >
>  >
>  >> - there is no explicit support for throwing exceptions, and no standard
>  >> exception class is defined. (Although it is trivial to define a handler
>  > that
>  >> throws.) This is intentional. I don't believe that we, at Boost, want
to
>  >> encourage this particular programming practice (assertions that throw.)
>  >>
>  > AFAIK, the differences between abort and throw are two-fold.
>  >
>  > On one hand, there are platform/compiler-dependent differences.
>  > Some enviroments (mostly Unix-like) don't allow you to get context
>  > information at the point of the throw, but, OTOH, supply a core-dump in
the
>  > case of abort(). On these enviroments, abort() is clearly superior.
>  > Other enviroments (Windows) do allow you to get context information at
the
>  > point of the throw and do not supply a *textual* core-dump for
post-morten
>  > debugging (although you can use JIT). On this enviroment, throw is
clearly
>  > superior.
> 
>  Strong disagreement!  Regular exception handling constructs can
>  interfere with your ability to do post-mortem debugging if you assert
>  by throwing an exception.

OK. I accept that exceptions are only viable IIF the debugger can stop right
after it is thrown; unless you need to application to keep running which is
really an application-level problem, not library-level.

> That makes asm { int 3 } or the equivalent
>  (which is what most of the built-in asserts do) much better on Windows
>  for assertions. Regular exception-handling constructs can also
>  interfere with asm{int 3}, but fortunately it's fairly easy to prevent
>  that in most cases. See libs/python/test/module_tail.cpp for the
>  trick.
> 
Oh yes, the good old DebugBreak() which is available in the Windows API. I
forgot about it.

All right, Borland's assert calls abort() unfortunately, which makes it
pretty useless; but the DebugBreak() trick is really good! I like it.

So I would settle for this 'trap into debugger' trick for assertion
behavior. No exceptions.

Fernando Cacciola


_______________________________________________
Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost