Re: [boost] [typeof] BOOST_TYPEOF_NESTED_TYPEDEF semicolon

From: Arkadiy Vertleyb (vertleyb_at_[hidden])
Date: 2007-03-14 14:55:13

"Steven Watanabe" <steven_at_[hidden]> wrote
> Arkadiy Vertleyb <vertleyb <at> hotmail.com> writes:
>>
>> "Steven Watanabe" <steven <at> providere-consulting.com> wrote
>>
>> > The definition of BOOST_TYPEOF_NESTED_TYPEDEF
>> > includes a semicolon at the end.  It should act like a normal 
>> > statement.
>>
>> There was a discussion in the past about whether or not such macros 
>> should
>> contain semicolons.  There was no agreement on this.  We decided to 
>> include
>> semicolons in typeof macros, where possible.  This way it can be used 
>> with
>> or without semicolon at the end.
>>
>> Of course this is not related to BOOST_TYPEOF or BOOST_AUTO, but
>> BOOST_TYPEOF_REGISTER_XXX macros, for example, all contain semicolons at 
>> the
>> end.
>>
> As far as I can make out from the standard, an extra
> semicolon is only permitted at function scope.  Trying
> to put a semicolon after BOOST_TYPEOF_NESTED_TYPEDEF
> inside a class or at namespace scope causes warnings
> on at least metrowerks 9.2 and como 4.3.3

I think you are right -- double semicolon cannot be used in all contexts, 
and this makes not using semicolon the only correct usage.

As far as I can remember, when this was discussed (I am no longer able to 
find the thread), Paul Mensonides was in strong disagreement with the idea 
of a macro usage looking "like a normal statement".

Frankly speaking I have no strong opinion on the subject.  I do believe, 
however, that this should be the subject of standartization inside Boost, so 
that the users don't become confused while working with multiple libraries. 
If such a guideline is accepted, we will change the typeof macros to comply.

Regards,
Arkadiy