Re: [boost] Cxx dual library

Subject: Re: [boost] Cxx dual library
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2016-06-06 17:18:11

Le 06/06/2016 à 10:52, Rob Stewart a écrit :
> On June 5, 2016 8:30:50 PM EDT, Edward Diener <eldiener_at_[hidden]> wrote:
>> On 6/5/2016 5:55 PM, Rob Stewart wrote:
>>>> It does involve more work and macros are still being used, although
>> not
>>>> to name the namespace. I honestly think that CXXD's solution is
>> cleaner
>>>> and more flexible. Lifting constructs which are normally accessed
>>>> through one namespace to another namespace in that way seems to me a
>>>> kludge. I am not sure of all the ramifications of doing this but I
>>>> would
>>>> be wary of doing such a thing myself.
> Vicente's approach, of I have it right, is pretty simple:
>
> namespace boost {
> namespace something {
>     using std::thread;
>     // or (conditionally selected)
>     using boost::thread;
> } }
>
> With that, boost::something::thread is the name to use in the user's code.
>
> The selection of what to import into the new namespace is managed by the preprocessor, so it can be overridden, too.
Right.
>
>> My thought is generally that CXXD represents the easiest approach and
>> that importing either side of a dual library's namespace into another
>> common namespace, no matter how it is controlled, does not represent
>> anything better than what CXXD has to offer.
> Allowing the user to just refer to boost::something::thread, rather than CXXD_THREAD::thread is less jarring to read, if nothing else. I don't think it offers much beyond that, though Vicente may have more information.
Sometimes It allows to rename the minor differences. CXXD would be able 
to do that by adding a them to another namespace let me call it 
cxdd::xxx, import whatever is needed from boost and rename the minoir 
differences there. Then change the selected namespace for the macro.
>
>> Furthermore, although I haven't had the time or knowledge to work
>> through all possible situations I believe that Vicente's approach could
>> have problems involving customization points for a library, ADL, and/or
>> template specializations.
> I don't think that's a problem for the library code itself and, since users are not generally permitted to open the std namespace, I don't think it would be a problem otherwise. Still, Vicente is best able to answer.
Specialization are not permited in csbl namespace. This is why in both 
approached we need the additional macros I suggested for CXXD.

Best,
Vicente