[boost] Re: assert() replacement?

From: Greg Colvin (gcolvin_at_[hidden])
Date: 1999-08-31 11:28:29

From: Valentin Bonnard <Bonnard.V_at_[hidden]>
> Greg Colvin wrote:
> 
> > From: Valentin Bonnard <Bonnard.V_at_[hidden]>
> > > ...
> > > I propose the following:
> > >
> > > // precondition: that debug_mode is defined
> > > #define BOOST_ASSERT_THROW(condition) \
> > >   (debug_mode ? boost::Utils::assert_throw(condition, __LINE__,
> > > __FILE__) : 0)
> > >
> > > namespace boost {
> > > namespace Utils {
> > >   struct AssertFailure : std::logic_error {
> > >      AssertFailure (long line, const char* file);
> > >   ...
> > >   };
> > >
> > >   inline void assert_throw (bool c, long line, const char* file)
> > >   { if (c) throw AssertFailure (line, file); }
> > > }
> > > using namespace Utils;
> > > }
> > 
> > So any user of Boost must define exactly one extern debug_mode in
> > order to link?
> 
> Yes. They must declare it in every TU which uses my macro 
> before uses of the macro.

Which means in every translation unit that includes any Boost header?

> There is no no-checks-by-default behaviour (there is no 
> default behaviour at all).
> 
> They can use an static constant but it isn't recommanded.
> They can use an auto variable.
> > And being a link-time constant, the code for the condition cannot
> > be compiled away?
> 
> You do it as you want: compile time constant, ``link time''
> constant, or even a variable. It's up to you.
> 
> I recommend a compile-time constant with external linkage.

You mean in each translation unit you would put something like this?

   const debug_mode = MY_DEBUG;

Doesn't that break the ODR?  Or am I confused again?