Re: [boost] suggestion on assertion macros

Subject: Re: [boost] suggestion on assertion macros
From: DE (satan66613_at_[hidden])
Date: 2010-03-15 12:59:00

hi all

on 14.03.2010 at 18:15
 Roland Bock wrote :
> Hmm. I use gcc (4.2.4) and I get the warning (-Wall -Wextra). That's why
> I proposed that code in the other part of this discussion (with great 
> help from Peter and Steven):

> #include <cassert>

> #ifdef NDEBUG
>   #ifdef assert
>      #undef assert
>      #define assert(cond) static_cast<void>(sizeof(cond? 0: 0));
>   #endif
> #endif

> int main() {
>   int i = 0;

>   assert(i);
> }

> This way, I get no warning about variable i being unused, it is even 
> being made sure that the condition for the assertion is verifiable and
> still the code results in nothing if NDEBUG is defined.

> I plan on using that myself. I think it would be useful for others, too.
i came to the same thing
this solution works perfect with msvc80 and i feel like going to
adopt it for my personal use

but i think you missed the order of macro directives
if i get it right it should be

#ifdef NDEBUG
  #ifdef assert
     #undef assert
  #endif    //swapped this and the following lines
  #define assert(cond) static_cast<void>(sizeof(cond? 0: 0));
#endif

and i agree that defining an "advanced" project-specific macro is
really a better solution than redefinition of 'assert()'

on improving assertions:
my only concern was to propose a solution to the warning issue while
NDEBUG is defined (and similar situations)
i picked 'assert()' only for illustration purposes
of course any other assert-like system may (or may not?? i believe it
does) be improved in this specific sense
my opinion is that specific assertions (like contract statements
mentioned) are defined the way the author prefer, i.e. there is no
typical restrictions on that
so the discussion on "improving assertions" or "contract programming
implementation" is not my concern for now and i leave it up to you guys

-- 
Pavel