Re: [Boost-bugs] [Boost C++ Libraries] #3517: [iostreams] stream<file_descriptor_source> closes supplied descriptor

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3517: [iostreams] stream<file_descriptor_source> closes supplied descriptor
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-06-15 08:10:46

#3517: [iostreams] stream<file_descriptor_source> closes supplied descriptor
--------------------------------------------------------------------+-------
 Reporter:  Alexander Churanov <alexanderchuranov+boost@…>          |       Owner:  turkanis 
     Type:  Bugs                                                    |      Status:  new      
Milestone:  Boost 1.41.0                                            |   Component:  iostreams
  Version:  Boost 1.39.0                                            |    Severity:  Problem  
 Keywords:                                                          |  
--------------------------------------------------------------------+-------

Comment(by danieljames):

 I think you're right, but I feel cautious about silently changing existing
 behaviour. I also dislike the boolean parameter. So I'd create a new
 constructor which takes flags to indicated if the handle should be closed.
 And maybe `close_on_exit` if someone wants it. I'd deprecate the existing
 constructor, so that it's only present if a macro is defined. That way
 we'd break the compile rather than subtly changing the code. What do you
 think of something like this? Am I being over-cautious?

 {{{
 namespace boost { namespace iostreams {

 enum file_handle_flags {
     close_handle, // maybe owns_handle?
     never_close_handle,
     close_handle_on_exit // Probably shouldn't be public.
 };

 class file_descriptor {
 public:
     typedef char                      char_type;
     typedef [implementation-defined]  category;
     file_descriptor( const std::string& pathname,
                      std::ios_base::open_mode mode =
                          std::ios_base::in | std::ios_base::out );

     file_descriptor( int fd, file_handle_flags);

     // Windows-only
     file_descriptor( HANDLE hFile, file_handle_flags);

 // Maybe something with a version number...
 #if defined(BOOST_IOSTREAMS_USE_DEPRECATED)
     file_descriptor( int fd, bool close_on_exit = false );

     // Windows-only
     file_descriptor( HANDLE hFile, bool close_on_exit = false );
 #endif

     bool is_open() const;
 };

 } } // End namespace boost::io

 }}}

 It'll be more verbose but I think it's worth it to clear up the ambiguity.
 Oh, and those constructors should probably have been `explicit`.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3517#comment:2>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.