Boost C++ Libraries: Ticket #3832: ptr_list const items

attachment set

matcatprg@… — Sun, 10 Jan 2010 20:08:20 GMT

attachment → main.cpp

test source code

attachment set

matcatprg@… — Sun, 10 Jan 2010 20:08:42 GMT

attachment → errors

g++ errors

anonymous — Sat, 06 Feb 2010 19:56:03 GMT

Found a workaround: use boost::shared_ptr with std::list.

anonymous — Mon, 08 Feb 2010 10:47:54 GMT

If you use the trunk repository, it should work just fine IICR.

-Thorsten

status changed; resolution set

matcatprg@… — Mon, 08 Feb 2010 20:49:58 GMT

status new → closed
resolution → fixed

The version from svn works fine.

Did you actually change something? Or was it that I didn't have the most recent version?

Matthew A. Todd

matcatprg@… — Mon, 08 Feb 2010 21:14:47 GMT

For clarification:

I just tested release 1.42, and the same error occurs there as well. So its something that has changed since then.

Matthew A. Todd

anonymous — Mon, 08 Feb 2010 23:12:06 GMT

Well, the problem is that I haven't comitted trunk to the release branch.

The change is not huge, but it might require a slight update to the docs too (not that the interfaces are affected).

The fix is basically just some meta-functions taking into account that T might be const, and if so, instantiate container<const void*> instead of container<void*>.

-Thorsten

anonymous — Thu, 12 May 2011 08:53:51 GMT

Is there any chance you could do the same with ptr_unordered_map? Should I open a new bug?

matcatprg@… — Mon, 16 May 2011 16:48:42 GMT

Replying to anonymous:

Is there any chance you could do the same with ptr_unordered_map? Should I open a new bug?

I'm a little busy with school at the moment, but I'd love to help. I'll go ahead and run the check once I get a chance (within next 3 or 4 weeks).

Matthew

matcatprg@… — Fri, 10 Jun 2011 22:10:25 GMT

I tested ptr_unordered_map<const char, const BASE*>. The test program compiled and ran both with and with out the consts. It also worked when the mapped type wasn't a pointer (i.e: const BASE).

For completeness, I went ahead and retested ptr_list as well. The full results are as follows:

container type      | trunk (72523)   | 1_46_1
------------------- | --------------- | ----------------------------------------
ptr_list            | works           | fails as before (fix not pushed to releases yet)
ptr_unordered_map   | works           | works

The only problems I had were with grokking how to use the container (my inexperience + doc vagueness) and trying to get insert() to work. Regarding the docs, more elaboration would be nice (e.g: what can be a pointer: the mapped type).

Regarding insert(), I couldn't tell exactly what was wrong, but it didn't have anything to do with const. I ended up using the "[]" operator to do insertion (which isn't mentioned in the doc but works and appears to be part of the intended behaviour based on ptr_map_adapter.hpp)

Let me know if you want more information or help.

Matthew

version changed

matt — Tue, 21 Aug 2012 18:42:09 GMT

version Boost 1.41.0 → Boost 1.50.0

Did this change ever land in the release branch? I'm still finding it with boost 1.50 installed with macports:

/opt/local/include/boost/ptr_container/ptr_sequence_adapter.hpp:249: error: invalid conversion from ‘const void*’ to ‘void*’

grep "BOOST_LIB_VERSION" /opt/local/include/boost/version.hpp => #define BOOST_LIB_VERSION "1_50"

g++ -v => gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)

Marshall Clow — Tue, 21 Aug 2012 20:03:06 GMT

This compiles correctly against the trunk, but fails against the release branch.

The error I get from clang is:

release/boost/ptr_container/ptr_sequence_adapter.hpp:249:37: error:
      reference to type 'const value_type' (aka 'void *const') could not bind to
      an lvalue of type 'value_type' (aka 'const BASE *')
            this->base().push_back( x );  // strong, commit
                                    ^
Downloads/main.cpp:37:13: note: in instantiation of member function
      'boost::ptr_sequence_adapter<const BASE, std::list<void *,
      std::allocator<void *>>, boost::heap_clone_allocator>::push_back'
      requested here
    intList.push_back(a);