Re: [boost] [BGL] Visual Studio 12 finish_edge() failure, general BOOST_TTI_HAS_MEMBER_FUNCTION failure?

Subject: Re: [boost] [BGL] Visual Studio 12 finish_edge() failure, general BOOST_TTI_HAS_MEMBER_FUNCTION failure?
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2014-04-10 02:18:16

On Tue, Apr 1, 2014 1:12 PM PDT Michael Behrns-Miller wrote:

>On 4/1/2014 8:45 AM, Edward Diener wrote:
>> On 4/1/2014 4:50 AM, Michael Behrns-Miller wrote:
>> On 4/1/2014 4:40 AM, Michael Behrns-Miller wrote:
>>> On 3/31/2014 6:30 PM, Edward Diener wrote:
>>> On 3/31/2014 1:27 PM, Michael Behrns-Miller wrote:
>>>> ...
>>>> Here's how BGL defines it:
>>>> 
>>>> -------------
>>>> 
>>>>      BOOST_TTI_HAS_MEMBER_FUNCTION(finish_edge)
>>>> 
>>>>      template <bool IsCallable> struct do_call_finish_edge {
>>>>        template <typename E, typename G, typename Vis>
>>>>        static void call_finish_edge(Vis& vis, const E& e, const G& g) {
>>>>          vis.finish_edge(e, g);
>>>>        }
>>>>      };
>>>> 
>>>>      template <> struct do_call_finish_edge<false> {
>>>>        template <typename E, typename G, typename Vis>
>>>>        static void call_finish_edge(Vis&, const E&, const G&) {}
>>>>      };
>>>> 
>>>>      template <typename E, typename G, typename Vis>
>>>>      void call_finish_edge(Vis& vis, const E& e, const G& g) { // Only
>>>> call if method exists
>>>> do_call_finish_edge<has_member_function_finish_edge<Vis,
>>>> void>::value>::call_finish_edge(vis, e, g);
>>>>      }
>>> 
>>> The invocation of has_member_function_finish_edge has to match the
>>> member function signature which you are invoking. If the member
>>> function signature for finish_edge is:
>>> 
>>> void finish_edge(const E&, const G&);
>>> 
>>> then your invocation for do_call_finish_edge must be:
>>> 
>>> do_call_finish_edge
>>>   <
>>>   has_member_function_finish_edge
>>>     <
>>>     Vis,
>>>     void,
>>>     boost::mpl::vector
>>>       <
>>>       const E&,
>>>       const G&
>>>       >
>>>     >
>>>   ::value
>>>   >::call_finish_edge(vis, e, g);
>>> 
>>> or
>>> 
>>> do_call_finish_edge
>>>   <
>>>   has_member_function_finish_edge
>>>     <
>>>     void Vis::* (const E&,const G&)
>>>     >
>>>   ::value
>>>   >::call_finish_edge(vis, e, g);
>>> 
>>> 
>>> _______________________________________________
>>> Unsubscribe & other changes:
>>> http://lists.boost.org/mailman/listinfo.cgi/boost
>>> 
>>> Thank you Edward.
>>> 
>>> The instantiation code was not mine, that is what is done by the BGL,
>>> here:
>>> 
>>>     boost\graph\depth_first_search.hpp
>>> 
>>> The instantiation code does not seem to match your recommendation.
>>> This simple DFS test fails:
>>> 
>>> https://svn.boost.org/trac/boost/attachment/ticket/9770/test.cc
>>> 
>>> So it sounds like BGL needs some patching to match your format. It
>>> should change from...
>>> 
>>> do_call_finish_edge<has_member_function_finish_edge<Vis,
>>> void>::value>::call_finish_edge(vis, e, g);
>>> 
>>> to...
>>> 
>>> do_call_finish_edge<has_member_function_finish_edge<void Vis::* (const
>>> E&,const G&)>::value>::call_finish_edge(vis, e, g);
>>> 
>>> Does that sound correct?
>> 
>> On the newer code, Visual Studio 12 gives me:
>> 
>>      boost_1_55_0/boost/graph/depth_first_search.hpp(86): error C2182:
>> 'abstract declarator' : illegal use of type 'void'
>> 
>> I am the developer for TTI. In your test case the actual VIZ struct has templated member functions, so I do not think has_member_function will find your templated functions. TTI is a compile-time mechanism for producing compile-time code. But even if it does not find the member functions at compile-time TTI should not produce a compile-time error so I definitely want to look at this situation.
>> 
>> As to why Visual Studio 12 gives that error I need to be able to reproduce your compile steps. I am an absolute novice with the Boost graph library. I think I need to build the library first, then run your test against it.
>> 
>> Jeremiah Willcock produced the changes in graph using TTI so he may have had a very good reason for using the original has_member_function signature, although it looks wrong to me on purely a TTI basis. Hopefully he will chime in on his change.
>> 
>> 
>> 
>> _______________________________________________
>> Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
>
>Thanks Edward, appreciate the feedback, I'll be monitoring.  In the meantime my workaround of making finish_edge() non-optional is working for me.  But of course I'd prefer not to have to change boost code before using.  :-)
>
>Sure appreciate all you guys do to develop and maintain the libraries, boost is just fantastic.

I wanted a way to test for equivalent signatures for the finish_edge member (copy vs. const ref, for example). I probably believed/saw somewhere that the syntax I used would do that. Is there a way to get a general "call ability" test for a member function using TTI?

-- Jeremiah Willcock