[Boost-bugs] [Boost C++ Libraries] #1044: Argument pack inaccessable in a functions return type

Subject: [Boost-bugs] [Boost C++ Libraries] #1044: Argument pack inaccessable in a functions return type
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2007-06-08 12:55:42

#1044: Argument pack inaccessable in a functions return type
------------------------------+---------------------------------------------
 Reporter:  johnmaddock       |       Owner:  daniel     
     Type:  Bugs              |      Status:  new        
Milestone:  To Be Determined  |   Component:  parameter  
  Version:                    |    Severity:  Showstopper
 Keywords:                    |  
------------------------------+---------------------------------------------
 An argument pack can not currently be used within the return type of a
 Boost.Parameter enabled function.  The following patch from Daniel Wallin
 fixes the issue:

 --- preprocessor.hpp    29 Sep 2006 00:31:28 -0000      1.5.2.9
 +++ preprocessor.hpp    27 May 2007 16:01:40 -0000
 @@ -149,7 +149,8 @@
        , typename Parameters::deduced_list
        , tag_keyword_arg
        , mpl::false_
 -    >::type type;
 +    >::type result;
 +    typedef typename mpl::first<result>::type type;
  };

 I also note that use of the argument pack within a
 BOOST_PARAMETER_FUNCTION-declared function is undocumented (but is
 supposed to be supported).

 Likewise I couldn't easily see any documentation on the names or the types
 of the parameters passed to such a function: the information is sort of
 there in the tutorial, but I had to resort to the preprocessed output to
 see what was going on.

 John Maddock.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1044>
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