Re: [boost] Defining compilers suggestion

From: Rob Stewart (stewart_at_[hidden])
Date: 2005-07-13 13:27:01

From: Edward Diener <eddielee_at_[hidden]>
> David Abrahams wrote:
> > Edward Diener <eddielee_at_[hidden]> writes:
> > 
> > 
> >   BOOST_COMPILER_VC == BOOST_COMPILER_VC71_VERSION
> > 
> > is more expressive than
> > 
> >   BOOST_MSVC_VERSION == 070100
> 
> It is more expressive than some long number because the former encompasses the 
> idea of a version of Microsoft VC++. I am trying to create a set of macros which 

Not at all.  That the comparison is against BOOST_MSVC_VERSION
makes quite clear the purpose of the expression.  Then, were it a
proper value, "070100" would clearly indicate a check for
v7.1SP0.  What's not expressive about that?

IOW, "070100" is far clearer than "BOOST_COMPILER_VC71_VERSION."

> equate to version numbers of compiler releases but which also allow boolean 
> comparisons for that release. That is why I have BOOST_COMPILER_XXX_VERSION and 
> BOOST_COMPILER_XXX_VERSION_HIGH for the former and BOOST_COMPILER_XXX, 
> BOOST_COMPILER_XXX_OR_HIGHER, and BOOST_COMPILER_XXX_OR_LOWER for the latter.

With numbers, you get all of that for free and there aren't any
ugly names!

> > Nor do I think 
> > 
> >   BOOST_COMPILER_VC <= BOOST_COMPILER_VC71_VERSION_HIGH
> > 
> > is an improvement over
> > 
> >   BOOST_MSVC_VERSION < 070200
> 
> I am sorry I can not make you see that and you still want programmers to refer 
> to version numbers as numbers.

I'm sorry we haven't gotten you to see the value of standardized
numbers.

> Let us suppose that one has workaround code only for BCB6. Currently, because 
> BCB6 encompasses definitions of __BORLANDC__ between 0x560 and 0x564, using 
> BOOST_WORKAROUND one would have to write to be completely correct:
> 
> #if BOOST_WORKAROUND(__BORLANDC__, >= 0x560) && BOOST_WORKAROUND(__BORLANDC__, 
> <= 0x564)
> // code
> #endif

No!  The point is that one would use a standardized macro like
BOOST_BCB_VERSION, not __BORLANDC__.  Furthermore, the comparison
would be >= 050600 and < 050700 (or, with the idea from another
branch of this thread, >= BOOST_VERSION(5,6,0) and <
BOOST_VERSION(5,7,0)).  That's flexible, standardized, and clear!

> whereas with my macros one would write:
> 
> #if BOOST_WORKAROUND(BOOST_COMPILER_BORLAND,BOOST_COMPILER_BCB6_VERSION) && 
> BOOST_WORKAROUND(BOOST_COMPILER_BORLAND,BOOST_COMPILER_BCB6_VERSION_HIGH)

That's incomprehensible.

> or even the much more succinct
> 
> #if BOOST_COMPILER_BCB6
> // code
> #endif
> 
> Granted that BOOST_WORKAROUND is more flexible than what I have presented, given 
> the practical case above, which I think is very prevalent in Boost code, which 
> do you really see as more understandable and easier to write ? My point is that 

Your last solution only works if one wants to create and maintain
an ever increasing set of named/versioned macros.  Given that the
conditional compilation being controlled isn't, in general so
neat as to apply to all patch levels of a single major version of
a compiler, your solution breaks down.

The alternative is comprehensible and provides the ability to
express every necessary combination.

-- 
Rob Stewart                           stewart_at_[hidden]
Software Engineer                     http://www.sig.com
Susquehanna International Group, LLP  using std::disclaimer;