[boost] Re: typeof

From: David Abrahams (dave_at_[hidden])
Date: 2004-05-05 11:26:14

"Arkadiy Vertleyb" <vertleyb_at_[hidden]> writes:

> "Daryle Walker" <darylew_at_[hidden]> wrote
>
>> Wouldn't the program need exactly one master type-of list?  Since C and
> C++
>> don't have cross-module consolidation, just text dumps of common files
> that
>> work by "coincidence", couldn't you break ODR by:
>>
>> File1.cpp:
>>     #include BOOST_TYPEOF_BEGIN_REGISTRATION()
>>     BOOST_TYPEOF_REGISTER_TYPE(greater_action);  //1
>>     BOOST_TYPEOF_REGISTER_TYPE(less_action);     //2
>>     BOOST_TYPEOF_REGISTER_TYPE(and_action);      //3
>>     #include BOOST_TYPEOF_END_REGISTRATION()
>>     int my_func1() { /*...*/}
>>
>> File2.cpp:
>>     #include BOOST_TYPEOF_BEGIN_REGISTRATION()
>>     BOOST_TYPEOF_REGISTER_TYPE(placeholder<1>);  //1
>>     BOOST_TYPEOF_REGISTER_TYPE(less_action);     //2 (only one the same)
>>     BOOST_TYPEOF_REGISTER_TYPE(greater_action);  //3
>>     #include BOOST_TYPEOF_END_REGISTRATION()
>>     int my_func2() { /*...*/}
>
> I could, but I use anonimous namespaces to avoid this.  This ensures every
> compilation unit has it's own set of encoding/decoding classes, and takes
> care of ODR.

I'm afraid it doesn't, technically, if typeof is used within a
template that's seen in multiple translation units.  That said, I'm
willing to accept it if it really works.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com