[Boost-bugs] [Boost C++ Libraries] #3326: struct tagging in constructor stops conditional construction without .swap call

Subject: [Boost-bugs] [Boost C++ Libraries] #3326: struct tagging in constructor stops conditional construction without .swap call
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-08-07 16:57:41

#3326: struct tagging in constructor stops conditional construction without .swap
call
-----------------------------------------------------------+----------------
 Reporter:  Andy Schneider <andrew.schneider@…>            |       Owner:  igaztanaga  
     Type:  Bugs                                           |      Status:  new         
Milestone:  Boost 1.40.0                                   |   Component:  interprocess
  Version:  Boost 1.39.0                                   |    Severity:  Cosmetic    
 Keywords:                                                 |  
-----------------------------------------------------------+----------------
 I'd like to do this:

    shared_memory_object shm_obj
       (isOwner  ? create_only  : open_only
       ,"shared_memory"              //name
       ,read_write                    //read-write mode
       );

 but I don't seem to be able to because create_only and open_only are tag
 structs.

 Instead I end up with something like this:

 shared_memory_object shm;

 if (isOwner)
 {
     shared_memory_object shm_obj (...)
     shm_obj.swap (shm);
 }
 else
 {
     shared_memory_object shm_obj (...)
     shm_obj.swap (shm);
 }

 which isn't as clean imho. What's the rational for a tag struct rather
 than enum?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3326>
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